- 08 Jan, 2024 1 commit
-
-
Yanqi Lv authored
I'm testing the performance of Pub/Sub command recently. I find if many clients unsubscribe or are killed simultaneously, Redis needs a long time to deal with it. In my experiment, I set 5000 clients and each client subscribes 100 channels. Then I call `client kill type pubsub` to simulate the situation where clients unsubscribe all channels at the same time and calculate the execution time. The result shows that it takes about 23s. I use the _perf_ and find that `listSearchKey` in `pubsubUnsubscribeChannel` costs more than 90% cpu time. I think we can optimize this situation. In this PR, I replace list with dict to track the clients subscribing the channel more efficiently. It changes O(N) to O(1) in the search phase. Then I repeat the experiment as above. The results are as follows. | | Execution Time(s) |used_memory(MB) | | :---------------- | :------: | :----: | | unstable(1bd0b549) | 23.734 | 65.41 | | optimize-pubsub | 0.288 | 67.66 | Thanks for #11595 , I use a no-value dict and the results shows that the performance improves significantly but the memory usage only increases slightly. Notice: - This PR will cause the performance degradation about 20% in `[p|s]subscribe` command but won't freeze Redis.
-
- 07 Jan, 2024 1 commit
-
-
debing.sun authored
## Issues and solutions from #12817 1. Touch ProcessingEventsWhileBlocked and calling moduleCount() without GIL in afterSleep() - Introduced: Version: 7.0.0 PR: #9963 - Harm Level: Very High If the module thread calls `RM_Yield()` before the main thread enters afterSleep(), and modifies `ProcessingEventsWhileBlocked`(+1), it will cause the main thread to not wait for GIL, which can lead to all kinds of unforeseen problems, including memory data corruption. - Initial / Abandoned Solution: * Added `__thread` specifier for ProcessingEventsWhileBlocked. `ProcessingEventsWhileBlocked` is used to protect against nested event processing, but event processing in the main thread and module threads should be completely independent and unaffected, so it is safer to use TLS. * Adding a cached module count to keep track of the current number of modules, to avoid having to use `dictSize()`. - Related Warnings: ``` WARNING: ThreadSanitizer: data race (pid=1136) Write of size 4 at 0x0001045990c0 by thread T4 (mutexes: write M0): #0 processEventsWhileBlocked networking.c:4135 (redis-server:arm64+0x10006d124) #1 RM_Yield module.c:2410 (redis-server:arm64+0x10018b66c) #2 bg_call_worker <null>:83232836 (blockedclient.so:arm64+0x16a8) Previous read of size 4 at 0x0001045990c0 by main thread: #0 afterSleep server.c:1861 (redis-server:arm64+0x100024f98) #1 aeProcessEvents ae.c:408 (redis-server:arm64+0x10000fd64) #2 aeMain ae.c:496 (redis-server:arm64+0x100010f0c) #3 main server.c:7220 (redis-server:arm64+0x10003f38c) ``` 2. aeApiPoll() is not thread-safe When using RM_Yield to handle events in a module thread, if the main thread has not yet entered `afterSleep()`, both the module thread and the main thread may touch `server.el` at the same time. - Introduced: Version: 7.0.0 PR: #9963 - Old / Abandoned Solution: Adding a new mutex to protect timing between after beforeSleep() and before afterSleep(). Defect: If the main thread enters the ae loop without any IO events, it will wait until the next timeout or until there is any event again, and the module thread will always hang until the main thread leaves the event loop. - Related Warnings: ``` SUMMARY: ThreadSanitizer: data race ae_kqueue.c:55 in addEventMask ================== ================== WARNING: ThreadSanitizer: data race (pid=14682) Write of size 4 at 0x000100b54000 by thread T9 (mutexes: write M0): #0 aeApiPoll ae_kqueue.c:175 (redis-server:arm64+0x100010588) #1 aeProcessEvents ae.c:399 (redis-server:arm64+0x10000fb84) #2 processEventsWhileBlocked networking.c:4138 (redis-server:arm64+0x10006d3c4) #3 RM_Yield module.c:2410 (redis-server:arm64+0x10018b66c) #4 bg_call_worker <null>:16042052 (blockedclient.so:arm64+0x169c) Previous write of size 4 at 0x000100b54000 by main thread: #0 aeApiPoll ae_kqueue.c:175 (redis-server:arm64+0x100010588) #1 aeProcessEvents ae.c:399 (redis-server:arm64+0x10000fb84) #2 aeMain ae.c:496 (redis-server:arm64+0x100010da8) #3 main server.c:7238 (redis-server:arm64+0x10003f51c) ``` ## The final fix as the comments: https://github.com/redis/redis/pull/12817#discussion_r1436427232 Optimized solution based on the above comment: First, we add `module_gil_acquring` to indicate whether the main thread is currently in the acquiring GIL state. When the module thread starts to yield, there are two possibilities(we assume the caller keeps the GIL): 1. The main thread is in the mid of beforeSleep() and afterSleep(), that is, `module_gil_acquring` is not 1 now. At this point, the module thread will wake up the main thread through the pipe and leave the yield, waiting for the next yield when the main thread may already in the acquiring GIL state. 2. The main thread is in the acquiring GIL state. The module thread release the GIL, yielding CPU to give the main thread an opportunity to start event processing, and then acquire the GIL again until the main thread releases it. This is what https://github.com/redis/redis/pull/12817#discussion_r1436427232 mentioned direction. --------- Co-authored-by:
Oran Agra <oran@redislabs.com>
-
- 28 Dec, 2023 1 commit
-
-
guybe7 authored
In case server.fsynced_reploff changed (e.g. flushAppendOnly set it to server.master_repl_offset in case there was nothing to fsync) we want to avoid sleeping before the next beforeSleep so we can call blockedBeforeSleep ASAP. without that, in case there's no incoming traffic, we could be waiting for the next cron timer event to wake us up.
-
- 27 Dec, 2023 1 commit
-
-
Chen Tianjie authored
We have achieved replacing `slots_to_keys` radix tree with key->slot linked list (#9356), and then replacing the list with slot specific dictionaries for keys (#11695). Shard channels behave just like keys in many ways, and we also need a slots->channels mapping. Currently this is still done by using a radix tree. So we should split `server.pubsubshard_channels` into 16384 dicts and drop the radix tree, just like what we did to DBs. Some benefits (basically the benefits of what we've done to DBs): 1. Optimize counting channels in a slot. This is currently used only in removing channels in a slot. But this is potentially more useful: sometimes we need to know how many channels there are in a specific slot when doing slot migration. Counting is now implemented by traversing the radix tree, and with this PR it will be as simple as calling `dictSize`, from O(n) to O(1). 2. The radix tree in the cluster has been removed. The shard channel names no longer require additional storage, which can save memory. 3. Potentially useful in slot migration, as shard channels are logically split by slots, thus making it easier to migrate, remove or add as a whole. 4. Avoid rehashing a big dict when there is a large number of channels. Drawbacks: 1. Takes more memory than using radix tree when there are relatively few shard channels. What this PR does: 1. in cluster mode, split `server.pubsubshard_channels` into 16384 dicts, in standalone mode, still use only one dict. 2. drop the `slots_to_channels` radix tree. 3. to save memory (to solve the drawback above), all 16384 dicts are created lazily, which means only when a channel is about to be inserted to the dict will the dict be initialized, and when all channels are deleted, the dict would delete itself. 5. use `server.shard_channel_count` to keep track of the number of all shard channels. --------- Co-authored-by:
Viktor Söderqvist <viktor.soderqvist@est.tech>
-
- 21 Dec, 2023 1 commit
-
-
Binbin authored
Let us see which version of redis this tool is part of. Similarly to redis-cli, redis-benchmark and redis-check-rdb redis-rdb-check and redis-aof-check are actually symlinks to redis, so they will directly use getVersion in server, the format became: ``` {title} v={redis_version} sha={sha}:{dirty} malloc={malloc} bits={bits} build={build} ``` Move cliVersion into cli_common, redis-cli and redis-benchmark will use it, and the format is not change: ``` {title} {redis_version} (git:{sha}) ```
-
- 15 Dec, 2023 1 commit
-
-
zhaozhao.zz authored
After #11695, we added two functions `rehashingStarted` and `rehashingCompleted` to the dict structure. We also registered two handlers for the main database's dict and expire structures. This allows the main database to record the dict in `rehashing` list when rehashing starts. Later, in `serverCron`, the `incrementallyRehash` function is continuously called to perform the rehashing operation. However, currently, when rehashing is completed, `rehashingCompleted` does not remove the dict from the `rehashing` list. This results in the `rehashing` list containing many invalid dicts. Although subsequent cron checks and removes dicts that don't require rehashing, it is still inefficient. This PR implements the functionality to remove the dict from the `rehashing` list in `rehashingCompleted`. This is achieved by adding `metadata` to the dict structure, which keeps track of its position in the `rehashing` list, allowing for quick removal. This approach avoids storing duplicate dicts in the `rehashing` list. Additionally, there are other modifications: 1. Whether in standalone or cluster mode, the dict in database is inserted into the rehashing linked list when rehashing starts. This eliminates the need to distinguish between standalone and cluster mode in `incrementallyRehash`. The function only needs to focus on the dicts in the `rehashing` list that require rehashing. 2. `rehashing` list is moved from per-database to Redis server level. This decouples `incrementallyRehash` from the database ID, and in standalone mode, there is no need to iterate over all databases, avoiding unnecessary access to databases that do not require rehashing. In the future, even if unsharded-cluster mode supports multiple databases, there will be no risk involved. 3. The insertion and removal operations of dict structures in the `rehashing` list are decoupled from `activerehashing` config. `activerehashing` only controls whether `incrementallyRehash` is executed in serverCron. There is no need for additional steps when modifying the `activerehashing` switch, as in #12705.
-
- 14 Dec, 2023 1 commit
-
-
Guillaume Koenig authored
The raxFind implementation uses a special pointer value (the address of a static string) as the "not found" value. It works as long as actual pointers were used. However we've seen usages where long long, non-pointer values have been used. It creates a risk that one of the long long value precisely is the address of the special "not found" value. This commit changes raxFind to return 1 or 0 to indicate elementhood, and take in a new void **value to optionally return the associated value. By extension, this also allow the RedisModule_DictSet/Replace operations to also safely insert integers instead of just pointers.
-
- 13 Dec, 2023 1 commit
-
-
Chen Tianjie authored
In INFO CLIENTS section, we already have blocked_clients and tracking_clients. We should add a new metric showing the number of pubsub connections, which helps performance monitoring and trouble shooting.
-
- 10 Dec, 2023 1 commit
-
-
Binbin authored
The change in dbSwapDatabases seems harmless. Because in non-clustered mode, dbBuckets calculations are strictly accurate and in cluster mode, we only have one DB. Modify it for uniformity (just like resize_cursor). The change in swapMainDbWithTempDb is needed in case we swap with the temp db, otherwise the overhead memory usage of db can be miscalculated. In addition we will swap all fields (including rehashing list), just for completeness (and reduce the chance of surprises in the future). Introduced in #12697.
-
- 06 Dec, 2023 1 commit
-
-
zhaozhao.zz authored
Additional optimizations for the eviction logic in #11695: To make the eviction logic clearer and decouple the number of sampled keys from the running mode (cluster or standalone). * When sampling in each database, we only care about the number of keys in the current database (not the dicts we sampled from). * If there are a insufficient number of keys in the current database (e.g. 10 times the value of `maxmemory_samples`), we can break out sooner (to avoid looping on a sparse database). * We'll never try to sample the db dicts more times than the number of non-empty dicts in the db (max 1 in non-cluster mode). And it also ensures that each database has a sufficient amount of sampled keys, so even if unsharded-cluster supports multiple databases, there won't be any issues. other changes: 1. keep track of the number of non-empty dicts in each database. 2. move key_count tracking into cumulativeKeyCountAdd rather than all it's callers --------- Co-authored-by:
Oran Agra <oran@redislabs.com>
-
- 28 Nov, 2023 1 commit
-
-
zhaozhao.zz authored
Introduced in #11695 . The tryResizeHashTables function gets stuck on the last non-empty slot while iterating through dictionaries. It does not restart from the beginning. The reason for this issue is a problem with the usage of dbIteratorNextDict: /* Returns next dictionary from the iterator, or NULL if iteration is complete. */ dict *dbIteratorNextDict(dbIterator *dbit) { if (dbit->next_slot == -1) return NULL; dbit->slot = dbit->next_slot; dbit->next_slot = dbGetNextNonEmptySlot(dbit->db, dbit->slot, dbit->keyType); return dbGetDictFromIterator(dbit); } When iterating to the last non-empty slot, next_slot is set to -1, causing it to loop indefinitely on that slot. We need to modify the code to ensure that after iterating to the last non-empty slot, it returns to the first non-empty slot. BTW, function tryResizeHashTables is actually iterating over slots that have keys. However, in its implementation, it leverages the dbIterator (which is a key iterator) to obtain slot and dictionary information. While this approach works fine, but it is not very intuitive. This PR also improves readability by changing the iteration to directly iterate over slots, thereby enhancing clarity.
-
- 23 Nov, 2023 1 commit
-
-
meiravgri authored
see discussion from after https://github.com/redis/redis/pull/12453 was merged ---- This PR replaces signals that are not considered async-signal-safe (AS-safe) with safe calls. #### **1. serverLog() and serverLogFromHandler()** `serverLog` uses unsafe calls. It was decided that we will **avoid** `serverLog` calls by the signal handlers when: * The signal is not fatal, such as SIGALRM. In these cases, we prefer using `serverLogFromHandler` which is the safe version of `serverLog`. Note they have different prompts: `serverLog`: `62220:M 26 Oct 2023 14:39:04.526 # <msg>` `serverLogFromHandler`: `62220:signal-handler (1698331136) <msg>` * The code was added recently. Calls to `serverLog` by the signal handler have been there ever since Redis exists and it hasn't caused problems so far. To avoid regression, from now we should use `serverLogFromHandler` #### **2. `snprintf` `fgets` and `strtoul`(base = 16) --------> `_safe_snprintf`, `fgets_async_signal_safe`, `string_to_hex`** The safe version of `snprintf` was taken from [here](https://github.com/twitter/twemcache/blob/8cfc4ca5e76ed936bd3786c8cc43ed47e7778c08/src/mc_util.c#L754) #### **3. fopen(), fgets(), fclose() --------> open(), read(), close()** #### **4. opendir(), readdir(), closedir() --------> open(), syscall(SYS_getdents64), close()** #### **5. Threads_mngr sync mechanisms** * waiting for the thread to generate stack trace: semaphore --------> busy-wait * `globals_rw_lock` was removed: as we are not using malloc and the semaphore anymore we don't need to protect `ThreadsManager_cleanups`. #### **6. Stacktraces buffer** The initial problem was that we were not able to safely call malloc within the signal handler. To solve that we created a buffer on the stack of `writeStacktraces` and saved it in a global pointer, assuming that under normal circumstances, the function `writeStacktraces` would complete before any thread attempted to write to it. However, **if threads lag behind, they might access this global pointer after it no longer belongs to the `writeStacktraces` stack, potentially corrupting memory.** To address this, various solutions were discussed [here](https://github.com/redis/redis/pull/12658#discussion_r1390442896) Eventually, we decided to **create a pipe** at server startup that will remain valid as long as the process is alive. We chose this solution due to its minimal memory usage, and since `write()` and `read()` are atomic operations. It ensures that stack traces from different threads won't mix. **The stacktraces collection process is now as follows:** * Cleaning the pipe to eliminate writes of late threads from previous runs. * Each thread writes to the pipe its stacktrace * Waiting for all the threads to mark completion or until a timeout (2 sec) is reached * Reading from the pipe to print the stacktraces. #### **7. Changes that were considered and eventually were dropped** * replace watchdog timer with a POSIX timer: according to [settimer man](https://linux.die.net/man/2/setitimer) > POSIX.1-2008 marks getitimer() and setitimer() obsolete, recommending the use of the POSIX timers API ([timer_gettime](https://linux.die.net/man/2/timer_gettime)(2), [timer_settime](https://linux.die.net/man/2/timer_settime)(2), etc.) instead. However, although it is supposed to conform to POSIX std, POSIX timers API is not supported on Mac. You can take a look here at the Linux implementation: [here](https://github.com/redis/redis/commit/c7562ee13546e504977372fdf40d33c3f86775a5 ) To avoid messing up the code, and uncertainty regarding compatibility, it was decided to drop it for now. * avoid using sds (uses malloc) in logConfigDebugInfo It was considered to print config info instead of using sds, however apparently, `logConfigDebugInfo` does more than just print the sds, so it was decided this fix is out of this issue scope. #### **8. fix Signal mask check** The check `signum & sig_mask` intended to indicate whether the signal is blocked by the thread was incorrect. Actually, the bit position in the signal mask corresponds to the signal number. We fixed this by changing the condition to: `sig_mask & (1L << (sig_num - 1))` #### **9. Unrelated changes** both `fork.tcl `and `util.tcl` implemented a function called `count_log_message` expecting different parameters. This caused confusion when trying to run daily tests with additional test parameters to run a specific test. The `count_log_message` in `fork.tcl` was removed and the calls were replaced with calls to `count_log_message` located in `util.tcl` --------- Co-authored-by:
Ozan Tezcan <ozantezcan@gmail.com> Co-authored-by:
Oran Agra <oran@redislabs.com>
-
- 22 Nov, 2023 2 commits
-
-
Josh Hershberg authored
Signed-off-by:
Josh Hershberg <yehoshua@redis.com>
-
Josh Hershberg authored
Move clusterState into cluster_legacy.h. In order to achieve this some "accessor" methods needed to be added to the cluster API and some other minor refactors. Signed-off-by:
Josh Hershberg <yehoshua@redis.com>
-
- 14 Nov, 2023 1 commit
-
-
Binbin authored
When using DB iterator, it will use dictInitSafeIterator to init a old safe dict iterator. When dbIteratorNext is used, it will jump to the next slot db dict when we are done a dict. During this process, we do not have any calls to dictResumeRehashing, which causes the dict's pauserehash to always be > 0. And at last, it will be returned directly in dictRehashMilliseconds, which causes us to have slot dict in a state where rehash cannot be completed. In the "expire scan should skip dictionaries with lot's of empty buckets" test, adding a `keys *` can reproduce the problem stably. `keys *` will call dbIteratorNext to trigger a traversal of all slot dicts. Added dbReleaseIterator and dbIteratorInitNextSafeIterator methods to call dictResetIterator. Issue was introduced in #11695.
-
- 09 Nov, 2023 1 commit
-
-
zhaozhao.zz authored
Introduced by #11695, the judgement should be dictIsRehashing.
-
- 01 Nov, 2023 1 commit
-
-
Chen Tianjie authored
In #12476 server.stat_client_qbuf_limit_disconnections was added. It is written in readQueryFromClient, which may be called by multiple threads when io-threads and io-threads-do-reads are turned on. Somehow we missed to make it an atomic variable.
-
- 27 Oct, 2023 1 commit
-
-
Harkrishn Patro authored
As part of #11695 independent dictionaries were introduced per slot. Time complexity to discover total no. of buckets across all dictionaries increased to O(N) with straightforward implementation of iterating over all dictionaries and adding dictBuckets of each. To optimize the time complexity, we could maintain a global counter at db level to keep track of the count of buckets and update it on the start and end of rehashing. --------- Co-authored-by:
Roshan Khatri <rvkhatri@amazon.com>
-
- 19 Oct, 2023 1 commit
-
-
Harkrishn Patro authored
Dictionary iterator logic in the `tryResizeHashTables` method is picking the next (incorrect) dictionary while the cursor is at a given slot. This could lead to some dictionary/slot getting skipped from resizing. Also stabilize the test. problem introduced recently in #11695
-
- 15 Oct, 2023 1 commit
-
-
Vitaly authored
This is an implementation of https://github.com/redis/redis/issues/10589 that eliminates 16 bytes per entry in cluster mode, that are currently used to create a linked list between entries in the same slot. Main idea is splitting main dictionary into 16k smaller dictionaries (one per slot), so we can perform all slot specific operations, such as iteration, without any additional info in the `dictEntry`. For Redis cluster, the expectation is that there will be a larger number of keys, so the fixed overhead of 16k dictionaries will be The expire dictionary is also split up so that each slot is logically decoupled, so that in subsequent revisions we will be able to atomically flush a slot of data. ## Important changes * Incremental rehashing - one big change here is that it's not one, but rather up to 16k dictionaries that can be rehashing at the same time, in order to keep track of them, we introduce a separate queue for dictionaries that are rehashing. Also instead of rehashing a single dictionary, cron job will now try to rehash as many as it can in 1ms. * getRandomKey - now needs to not only select a random key, from the random bucket, but also needs to select a random dictionary. Fairness is a major concern here, as it's possible that keys can be unevenly distributed across the slots. In order to address this search we introduced binary index tree). With that data structure we are able to efficiently find a random slot using binary search in O(log^2(slot count)) time. * Iteration efficiency - when iterating dictionary with a lot of empty slots, we want to skip them efficiently. We can do this using same binary index that is used for random key selection, this index allows us to find a slot for a specific key index. For example if there are 10 keys in the slot 0, then we can quickly find a slot that contains 11th key using binary search on top of the binary index tree. * scan API - in order to perform a scan across the entire DB, the cursor now needs to not only save position within the dictionary but also the slot id. In this change we append slot id into LSB of the cursor so it can be passed around between client and the server. This has interesting side effect, now you'll be able to start scanning specific slot by simply providing slot id as a cursor value. The plan is to not document this as defined behavior, however. It's also worth nothing the SCAN API is now technically incompatible with previous versions, although practically we don't believe it's an issue. * Checksum calculation optimizations - During command execution, we know that all of the keys are from the same slot (outside of a few notable exceptions such as cross slot scripts and modules). We don't want to compute the checksum multiple multiple times, hence we are relying on cached slot id in the client during the command executions. All operations that access random keys, either should pass in the known slot or recompute the slot. * Slot info in RDB - in order to resize individual dictionaries correctly, while loading RDB, it's not enough to know total number of keys (of course we could approximate number of keys per slot, but it won't be precise). To address this issue, we've added additional metadata into RDB that contains number of keys in each slot, which can be used as a hint during loading. * DB size - besides `DBSIZE` API, we need to know size of the DB in many places want, in order to avoid scanning all dictionaries and summing up their sizes in a loop, we've introduced a new field into `redisDb` that keeps track of `key_count`. This way we can keep DBSIZE operation O(1). This is also kept for O(1) expires computation as well. ## Performance This change improves SET performance in cluster mode by ~5%, most of the gains come from us not having to maintain linked lists for keys in slot, non-cluster mode has same performance. For workloads that rely on evictions, the performance is similar because of the extra overhead for finding keys to evict. RDB loading performance is slightly reduced, as the slot of each key needs to be computed during the load. ## Interface changes * Removed `overhead.hashtable.slot-to-keys` to `MEMORY STATS` * Scan API will now require 64 bits to store the cursor, even on 32 bit systems, as the slot information will be stored. * New RDB version to support the new op code for SLOT information. --------- Co-authored-by:
Vitaly Arbuzov <arvit@amazon.com> Co-authored-by:
Harkrishn Patro <harkrisp@amazon.com> Co-authored-by:
Roshan Khatri <rvkhatri@amazon.com> Co-authored-by:
Madelyn Olson <madelyneolson@gmail.com> Co-authored-by:
Oran Agra <oran@redislabs.com>
-
- 03 Oct, 2023 1 commit
-
-
Madelyn Olson authored
We use the C standard assert() in various places in the codebase, which requires NDEBUG to be undefined. We introduced the redisassert.h file in order to allow low level files to access the assert that maps to serverPanic, but this was only applied tactically and is not available broadly. This PR removes all usage of the standard library asserts and replaces them with an assert that maps to serverPanic. It makes us immune to accidentally setting the NDEBUG flag preventing assertions. I also marked marked the server asserts as "likely" to not execute. I spot checked various points in the code, and it didn't change the code layout on my x86 mac, but it is more consistent with redisassert.h and seems more correct overall.
-
- 28 Sep, 2023 1 commit
-
-
Viktor Söderqvist authored
In a long printf call with many placeholders, it's hard to see which argument belongs to which placeholder. The long printf-like calls in the INFO and CLIENT commands are rewritten into pairs of (format, argument). These pairs are then rewritten to a single call with a long format string and a long list of arguments, using a macro called FMTARGS. The file `fmtargs.h` is added to the repo. Co-authored-by:
Madelyn Olson <34459052+madolson@users.noreply.github.com>
-
- 24 Sep, 2023 1 commit
-
-
meiravgri authored
In this PR we are adding the functionality to collect all the process's threads' backtraces. ## Changes made in this PR ### **introduce threads mngr API** The **threads mngr API** which has 2 abilities: * `ThreadsManager_init() `- register to SIGUSR2. called on the server start-up. * ` ThreadsManager_runOnThreads()` - receives a list of a pid_t and a callback, tells every thread in the list to invoke the callback, and returns the output collected by each invocation. **Elaborating atomicvar API** * `atomicIncrGet(var,newvalue_var,count) `-- Increment and get the atomic counter new value * `atomicFlagGetSet` -- Get and set the atomic counter value to 1 ### **Always set SIGALRM handler** SIGALRM handler prints the process's stacktrace to the log file. Up until now, it was set only if the `server.watchdog_period` > 0. This can be also useful if debugging is needed. However, in situations where the server can't get requests, (a deadlock, for example) we weren't able to change the signal handler. To make it available at run time we set SIGALRM handler on server startup. The signal handler name was changed to a more general `sigalrmSignalHandler`. ### **Print all the process' threads' stacktraces** `logStackTrace()` now calls `writeStacktraces()`, instead of logging the current thread stacktrace. `writeStacktraces()`: * On Linux systems we use the threads manager API to collect the backtraces of all the process' threads. To get the `tids` list (threads ids) we read the `/proc/<redis-server-pid>/tasks` file which includes a list of directories. Each directory name corresponds to one tid (including the main thread). For each thread, we also need to check if it can get the signal from the threads manager (meaning it is not blocking/ignoring that signal). We send the threads manager this tids list and `collect_stacktrace_data()` callback, which collects the thread's backtrace addresses, its name, and tid. * On other systems, the behavior remained as it was (writing only the current thread stacktrace to the log file). ## compatibility notes 1. **The threads mngr API is only supported in linux.** 2. glibc earlier than 2.3 We use `syscall(SYS_gettid)` and `syscall(SYS_tgkill...)` because their dedicated alternatives (`gettid()` and `tgkill`) were added in glibc 2.3. ## Output example Each thread backtrace will have the following format: `<tid> <thread_name> [additional_info]` * **tid**: as read from the `/proc/<redis-server-pid>/tasks` file * **thread_name**: the tread name as it is registered in the os/ * **additional_info**: Sometimes we want to add specific information about one of the threads. currently. it is only used to mark the thread that handles the backtraces collection by adding "*". In case of crash - this also indicates which thread caused the crash. The handling thread in won't necessarily appear first. ``` ------ STACK TRACE ------ EIP: /lib/aarch64-linux-gnu/libc.so.6(epoll_pwait+0x9c)[0xffffb9295ebc] 67089 redis-server * linux-vdso.so.1(__kernel_rt_sigreturn+0x0)[0xffffb9437790] /lib/aarch64-linux-gnu/libc.so.6(epoll_pwait+0x9c)[0xffffb9295ebc] redis-server *:6379(+0x75e0c)[0xaaaac2fe5e0c] redis-server *:6379(aeProcessEvents+0x18c)[0xaaaac2fe6c00] redis-server *:6379(aeMain+0x24)[0xaaaac2fe7038] redis-server *:6379(main+0xe0c)[0xaaaac3001afc] /lib/aarch64-linux-gnu/libc.so.6(+0x273fc)[0xffffb91d73fc] /lib/aarch64-linux-gnu/libc.so.6(__libc_start_main+0x98)[0xffffb91d74cc] redis-server *:6379(_start+0x30)[0xaaaac2fe0370] 67093 bio_lazy_free /lib/aarch64-linux-gnu/libc.so.6(+0x79dfc)[0xffffb9229dfc] /lib/aarch64-linux-gnu/libc.so.6(pthread_cond_wait+0x208)[0xffffb922c8fc] redis-server *:6379(bioProcessBackgroundJobs+0x174)[0xaaaac30976e8] /lib/aarch64-linux-gnu/libc.so.6(+0x7d5c8)[0xffffb922d5c8] /lib/aarch64-linux-gnu/libc.so.6(+0xe5d1c)[0xffffb9295d1c] 67091 bio_close_file /lib/aarch64-linux-gnu/libc.so.6(+0x79dfc)[0xffffb9229dfc] /lib/aarch64-linux-gnu/libc.so.6(pthread_cond_wait+0x208)[0xffffb922c8fc] redis-server *:6379(bioProcessBackgroundJobs+0x174)[0xaaaac30976e8] /lib/aarch64-linux-gnu/libc.so.6(+0x7d5c8)[0xffffb922d5c8] /lib/aarch64-linux-gnu/libc.so.6(+0xe5d1c)[0xffffb9295d1c] 67092 bio_aof /lib/aarch64-linux-gnu/libc.so.6(+0x79dfc)[0xffffb9229dfc] /lib/aarch64-linux-gnu/libc.so.6(pthread_cond_wait+0x208)[0xffffb922c8fc] redis-server *:6379(bioProcessBackgroundJobs+0x174)[0xaaaac30976e8] /lib/aarch64-linux-gnu/libc.so.6(+0x7d5c8)[0xffffb922d5c8] /lib/aarch64-linux-gnu/libc.so.6(+0xe5d1c)[0xffffb9295d1c] 67089:signal-handler (1693824528) -------- ```
-
- 30 Aug, 2023 1 commit
-
-
Chen Tianjie authored
Add these INFO metrics: * client_query_buffer_limit_disconnections * client_output_buffer_limit_disconnections Sometimes it is useful to monitor whether clients reaches size limit of query buffer and output buffer, to decide whether we need to adjust the buffer size limit or reduce client query payload.
-
- 20 Aug, 2023 1 commit
-
-
meiravgri authored
This PR purpose is to make the crash report process thread safe. main changes include: 1. `setupSigSegvHandler()` is introduced to initialize the signal handler. This function first initializes the signal handler mutex (if not initialized yet) and then registers the process to the signal handler. 2. **sigsegvHandler** flags : SA_NODEFER - don't add the signal to the process signal mask. We use this flag because we want to be able to handle a second call to the signal manually. removed SA_RESETHAND: this flag resets the signal handler function upon the first entrance to the registered function. The reason to use this flag is to protect from recursively entering the signal handler by the same thread. But, it also means that if a second thread crashes while handling a signal, the process will be terminated immediately and we won't get the crash report. In this PR we discard this flag. The signal handler guard described below purpose is to solve the above issues. 3. Add a **signal handler lock** with ERRORCHECK attributes. The lock's purpose is to ensure that only one thread generates a crash report. Once a second thread enters the signal handler it will be blocked. We use the ERRORCHECK lock in order to protect from possible deadlock in case the thread handling the crash gets a signal. In the latest scenario, we log what we have collected until the handler crashed. At the end of the crash report we reset the signal handler SIG_DFL, with no flags, and rethrow the signal to generate a core dump (if enabled) and exit the process. During the work on this PR we wanted to understand the historical reasons for how crash is handled. With respect to the choice of the flag, we believe the **SA_RESETHAND** was not added for any specific purpose. **SA_ONSTACK** which is removed here from bugReportEnd(), was originally also set in the initial registration to signal handler, but removed in 3ada43e7. In addition, it was removed from another location in deee2c1e with the following description, which is also relevant to why it should be removed from bugReportEnd: > it seems to be some valgrind bug with SA_ONSTACK. > SA_ONSTACK seems unneeded since WD is not recursive (SA_NODEFER was removed), > also, not sure if it's even valid without a call to sigaltstack()
-
- 05 Aug, 2023 1 commit
-
-
zhaozhao.zz authored
Fix the assertion when a busy script (timeout) signal ready keys (like LPUSH), and then an arbitrary client's `allow-busy` command steps into `handleClientsBlockedOnKeys` try wake up clients blocked on keys (like BLPOP). Reproduction process: 1. start a redis with aof `./redis-server --appendonly yes` 2. exec blpop `127.0.0.1:6379> blpop a 0` 3. use another client call a busy script and this script push the blocked key `127.0.0.1:6379> eval "redis.call('lpush','a','b') while(1) do end" 0` 4. user a new client call an allow-busy command like auth `127.0.0.1:6379> auth a` BTW, this issue also break the atomicity of script. This bug has been around for many years, the old versions only have the atomic problem, only 7.0/7.2 has the assertion problem. Co-authored-by:
Oran Agra <oran@redislabs.com>
-
- 25 Jul, 2023 1 commit
-
-
zhaozhao.zz authored
A bug introduced in #11657 (7.2 RC1), causes client-eviction (#8687) and INFO to have inaccurate memory usage metrics of MONITOR clients. Because the type in `c->type` and the type in `getClientType()` are confusing (in the later, `CLIENT_TYPE_NORMAL` not `CLIENT_TYPE_SLAVE`), the comment we wrote in `updateClientMemUsageAndBucket` was wrong, and in fact that function didn't skip monitor clients. And since it doesn't skip monitor clients, it was wrong to delete the call for it from `replicationFeedMonitors` (it wasn't a NOP). That deletion could mean that the monitor client memory usage is not always up to date (updated less frequently, but still a candidate for client eviction).
-
- 25 Jun, 2023 1 commit
-
-
Binbin authored
The new blockedBeforeSleep was added in #12337, it breaks the order in 2ecb5edf. This may be related to #2288, quoted from comment in #2288: ``` Moreover the clusterBeforeSleep() call was misplaced at the end of the chain of the beforeSleep() call in redis.c. It should be at the top, before processing un blocking clients. This is exactly the reason in the specific instance of the bug as reported, why the state was not updated in time before clients served. ```
-
- 22 Jun, 2023 1 commit
-
-
guybe7 authored
Apart from adding the missing coverage, this PR also adds `blockedBeforeSleep` that gathers all block-related functions from `beforeSleep` The order inside `blockedBeforeSleep` is different: now `handleClientsBlockedOnKeys` (which may unblock clients) is called before `processUnblockedClients` (which handles unblocked clients). It makes sense to have this order. There are no visible effects of the wrong ordering, except some cleanups of the now-unblocked client would have happen in the next `beforeSleep` (will now happen in the current one) The reason we even got into it is because i triggers an assertion in logresreq.c (breaking the assumption that `unblockClient` is called **before** actually flushing the reply to the socket): `handleClientsBlockedOnKeys` is called, then it calls `moduleUnblockClientOnKey`, which calls `moduleUnblockClient`, which adds the client to `moduleUnblockedClients` back to `beforeSleep`, we call `handleClientsWithPendingWritesUsingThreads`, it writes the data of buf to the client, so `client->bufpos` became 0 On the next `beforeSleep`, we call `moduleHandleBlockedClients`, which calls `unblockClient`, which calls `reqresAppendResponse`, triggering the assert. (because the `bufpos` is 0) - see https://github.com/redis/redis/pull/12301#discussion_r1226386716
-
- 20 Jun, 2023 1 commit
-
-
Oran Agra authored
When a connection that's subscribe to a channel emits PUBLISH inside MULTI-EXEC, the push notification messes up the EXEC response. e.g. MULTI, PING, PUSH foo bar, PING, EXEC the EXEC's response will contain: PONG, {message foo bar}, 1. and the second PONG will be delivered outside the EXEC's response. Additionally, this PR changes the order of responses in case of a plain PUBLISH (when the current client also subscribed to it), by delivering the push after the command's response instead of before it. This also affects modules calling RM_PublishMessage in a similar way, so that we don't run the risk of getting that push mixed together with the module command's response.
-
- 11 Jun, 2023 1 commit
-
-
YaacovHazan authored
In 7.2, After 971b177f we make sure (assert) that the duration has been recorded when resetting the client. This is not true for rejected commands. The use case I found is a blocking command that an ACL rule changed before it was unblocked, and while reprocessing it, the command rejected and triggered the assert. The PR reset the command duration inside rejectCommand / rejectCommandSds. Co-authored-by:
Oran Agra <oran@redislabs.com>
-
- 24 May, 2023 1 commit
-
-
judeng authored
postpone the initialization of oject's lru&lfu until it is added to the db as a value object (#11626) This pr can get two performance benefits: 1. Stop redundant initialization when most robj objects are created 2. LRU_CLOCK will no longer be called in io threads, so we can avoid the `atomicGet` Another code optimization: deleted the redundant judgment in dbSetValue, no matter in LFU or LRU, the lru field inold robj is always the freshest (it is always updated in lookupkey), so we don't need to judge if in LFU
-
- 12 May, 2023 1 commit
-
-
Chen Tianjie authored
The measured latency(duration) includes the list below, which can be shown by `INFO STATS`. ``` eventloop_cycles // ever increasing counter eventloop_duration_sum // cumulative duration of eventloop in microseconds eventloop_duration_cmd_sum // cumulative duration of executing commands in microseconds instantaneous_eventloop_cycles_per_sec // average eventloop count per second in recent 1.6s instantaneous_eventloop_duration_usec // average single eventloop duration in recent 1.6s ``` Also added some experimental metrics, which are shown only when `INFO DEBUG` is called. This section isn't included in the default INFO, or even in `INFO ALL` and the fields in this section can change in the future without considering backwards compatibility. ``` eventloop_duration_aof_sum // cumulative duration of writing AOF eventloop_duration_cron_sum // cumulative duration cron jobs (serverCron, beforeSleep excluding IO and AOF) eventloop_cmd_per_cycle_max // max number of commands executed in one eventloop eventloop_duration_max // max duration of one eventloop ``` All of these are being reset by CONFIG RESETSTAT
-
- 06 May, 2023 1 commit
-
-
zhaozhao.zz authored
When master reboot from RDB, if rsi in RDB is valid we should not free replication backlog, even if master_repl_offset or repl-offset is 0. Since if master doesn't send any data to replicas master_repl_offset is 0, it's a valid number. A clear example: 1. start a master and apply some write commands, the master's master_repl_offset is 0 since it has no replicas. 2. stop write commands on master, and start another instance and replicaof the master, trigger an FULLRESYNC 3. the master's master_repl_offset is still 0 (set a large number for repl-ping-replica-period), do BGSAVE and restart the master 4. master load master_repl_offset from RDB's rsi and it's still 0, and we should make sure replica can partially resync with master.
-
- 03 May, 2023 1 commit
-
-
Madelyn Olson authored
Technically declaring a prototype with an empty declaration has been deprecated since the early days of C, but we never got a warning for it. C2x will apparently be introducing a breaking change if you are using this type of declarator, so Clang 15 has started issuing a warning with -pedantic. Although not apparently a problem for any of the compiler we build on, if feels like the right thing is to properly adhere to the C standard and use (void).
-
- 24 Apr, 2023 2 commits
-
-
zhaozhao.zz authored
Every time when accept a connection, we add the client to `server.clients` list's tail, but in `clientsCron` we rotate the tail to head at first, and then process the head. It means that the "new" client would be processed before "old" client, moreover if connections established and then freed frequently, the "old" client may have no chance to be processed. To fix it, we need take a fair way to iterate the list, that is take the current head and process, and then rotate the head to tail, thus we can make sure all clients could be processed step by step. p.s. client has `client_list_node` pointer, we don't need put the current client to head to avoid O(N) when remove it.
-
Binbin authored
Since we do report the RDB error in below: ``` serverLog(LL_WARNING,"Error trying to save the DB, can't exit."); if (server.supervised_mode == SUPERVISED_SYSTEMD) redisCommunicateSystemd("STATUS=Error trying to save the DB, can't exit.\n"); goto error; ``` This may be an overlook in #6052
-
- 20 Apr, 2023 1 commit
-
-
YaacovHazan authored
We currently do not allow the use of bool type in redis project. We didn't catch it in script.c because we included hdr_histogram.h in server.h Removing it (but still having it in some c files) reducing the chance to miss the usage of bool type in the future and catch it in compiling stage. It also removes the dependency on hdr_histogram for every unit that includes server.h
-
- 19 Apr, 2023 1 commit
-
-
Oran Agra authored
1. it's a bad idea to print these errors and exit after daemonization (if we'll exit, the failure may not be detected) 2. it's not nice to exit (or even do the check that uses `fork`) after modules already started (could create threads, or do some changes)
-
- 18 Apr, 2023 1 commit
-
-
sundb authored
This PR is to fix the compilation warnings and errors generated by the latest complier toolchain, and to add a new runner of the latest toolchain for daily CI. ## Fix various compilation warnings and errors 1) jemalloc.c COMPILER: clang-14 with FORTIFY_SOURCE WARNING: ``` src/jemalloc.c:1028:7: warning: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Wstring-concatenation] "/etc/malloc.conf", ^ src/jemalloc.c:1027:3: note: place parentheses around the string literal to silence warning "\"name\" of the file referenced by the symbolic link named " ^ ``` REASON: the compiler to alert developers to potential issues with string concatenation that may miss a comma, just like #9534 which misses a comma. SOLUTION: use `()` to tell the compiler that these two line strings are continuous. 2) config.h COMPILER: clang-14 with FORTIFY_SOURCE WARNING: ``` In file included from quicklist.c:36: ./config.h:319:76: warning: attribute declaration must precede definition [-Wignored-attributes] char *strcat(char *restrict dest, const char *restrict src) __attribute__((deprecated("please avoid use of unsafe C functions. prefer use of redis_strlcat instead"))); ``` REASON: Enabling _FORTIFY_SOURCE will cause the compiler to use `strcpy()` with check, it results in a deprecated attribute declaration after including <features.h>. SOLUTION: move the deprecated attribute declaration from config.h to fmacro.h before "#include <features.h>". 3) networking.c COMPILER: GCC-12 WARNING: ``` networking.c: In function ‘addReplyDouble.part.0’: networking.c:876:21: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 876 | dbuf[start] = '$'; | ^ networking.c:868:14: note: at offset -5 into destination object ‘dbuf’ of size 5152 868 | char dbuf[MAX_LONG_DOUBLE_CHARS+32]; | ^ networking.c:876:21: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 876 | dbuf[start] = '$'; | ^ networking.c:868:14: note: at offset -6 into destination object ‘dbuf’ of size 5152 868 | char dbuf[MAX_LONG_DOUBLE_CHARS+32]; ``` REASON: GCC-12 predicts that digits10() may return 9 or 10 through `return 9 + (v >= 1000000000UL)`. SOLUTION: add an assert to let the compiler know the possible length; 4) redis-cli.c & redis-benchmark.c COMPILER: clang-14 with FORTIFY_SOURCE WARNING: ``` redis-benchmark.c:1621:2: warning: embedding a directive within macro arguments has undefined behavior [-Wembedded-directive] #ifdef USE_OPENSSL redis-cli.c:3015:2: warning: embedding a directive within macro arguments has undefined behavior [-Wembedded-directive] #ifdef USE_OPENSSL ``` REASON: when _FORTIFY_SOURCE is enabled, the compiler will use the print() with check, which is a macro. this may result in the use of directives within the macro, which is undefined behavior. SOLUTION: move the directives-related code out of `print()`. 5) server.c COMPILER: gcc-13 with FORTIFY_SOURCE WARNING: ``` In function 'lookupCommandLogic', inlined from 'lookupCommandBySdsLogic' at server.c:3139:32: server.c:3102:66: error: '*(robj **)argv' may be used uninitialized [-Werror=maybe-uninitialized] 3102 | struct redisCommand *base_cmd = dictFetchValue(commands, argv[0]->ptr); | ~~~~^~~ ``` REASON: The compiler thinks that the `argc` returned by `sdssplitlen()` could be 0, resulting in an empty array of size 0 being passed to lookupCommandLogic. this should be a false positive, `argc` can't be 0 when strings are not NULL. SOLUTION: add an assert to let the compiler know that `argc` is positive. 6) sha1.c COMPILER: gcc-12 WARNING: ``` In function ‘SHA1Update’, inlined from ‘SHA1Final’ at sha1.c:195:5: sha1.c:152:13: warning: ‘SHA1Transform’ reading 64 bytes from a region of size 0 [-Wstringop-overread] 152 | SHA1Transform(context->state, &data[i]); | ^ sha1.c:152:13: note: referencing argument 2 of type ‘const unsigned char[64]’ sha1.c: In function ‘SHA1Final’: sha1.c:56:6: note: in a call to function ‘SHA1Transform’ 56 | void SHA1Transform(uint32_t state[5], const unsigned char buffer[64]) | ^ In function ‘SHA1Update’, inlined from ‘SHA1Final’ at sha1.c:198:9: sha1.c:152:13: warning: ‘SHA1Transform’ reading 64 bytes from a region of size 0 [-Wstringop-overread] 152 | SHA1Transform(context->state, &data[i]); | ^ sha1.c:152:13: note: referencing argument 2 of type ‘const unsigned char[64]’ sha1.c: In function ‘SHA1Final’: sha1.c:56:6: note: in a call to function ‘SHA1Transform’ 56 | void SHA1Transform(uint32_t state[5], const unsigned char buffer[64]) ``` REASON: due to the bug[https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80922], when enable LTO, gcc-12 will not see `diagnostic ignored "-Wstringop-overread"`, resulting in a warning. SOLUTION: temporarily set SHA1Update to noinline to avoid compiler warnings due to LTO being enabled until the above gcc bug is fixed. 7) zmalloc.h COMPILER: GCC-12 WARNING: ``` In function ‘memset’, inlined from ‘moduleCreateContext’ at module.c:877:5, inlined from ‘RM_GetDetachedThreadSafeContext’ at module.c:8410:5: /usr/include/x86_64-linux-gnu/bits/string_fortified.h:59:10: warning: ‘__builtin_memset’ writing 104 bytes into a region of size 0 overflows the destination [-Wstringop-overflow=] 59 | return __builtin___memset_chk (__dest, __ch, __len, ``` REASON: due to the GCC-12 bug [https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96503], GCC-12 cannot see alloc_size, which causes GCC to think that the actual size of memory is 0 when checking with __glibc_objsize0(). SOLUTION: temporarily set malloc-related interfaces to `noinline` to avoid compiler warnings due to LTO being enabled until the above gcc bug is fixed. ## Other changes 1) Fixed `ps -p [pid]` doesn't output `<defunct>` when using procps 4.x causing `replication child dies when parent is killed - diskless` test to fail. 2) Add a new fortify CI with GCC-13 and ubuntu-lunar docker image.
-