2012-11-08 18:25:23 +01:00
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/*
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2024-08-14 17:20:36 +01:00
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* Copyright (c) 2009-2012, Redis Ltd.
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2012-11-08 18:25:23 +01:00
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Redis nor the names of its contributors may be used
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* to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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2019-11-20 20:18:00 -05:00
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#ifndef __BIO_H
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#define __BIO_H
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2020-12-23 19:13:12 -08:00
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typedef void lazy_free_fn(void *args[]);
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2011-09-13 15:59:48 +02:00
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/* Exported API */
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void bioInit(void);
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2022-08-26 19:09:23 +03:00
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unsigned long bioPendingJobsOfType(int type);
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Implementing the WAITAOF command (issue #10505) (#11713)
Implementing the WAITAOF functionality which would allow the user to
block until a specified number of Redises have fsynced all previous write
commands to the AOF.
Syntax: `WAITAOF <num_local> <num_replicas> <timeout>`
Response: Array containing two elements: num_local, num_replicas
num_local is always either 0 or 1 representing the local AOF on the master.
num_replicas is the number of replicas that acknowledged the a replication
offset of the last write being fsynced to the AOF.
Returns an error when called on replicas, or when called with non-zero
num_local on a master with AOF disabled, in all other cases the response
just contains number of fsync copies.
Main changes:
* Added code to keep track of replication offsets that are confirmed to have
been fsynced to disk.
* Keep advancing master_repl_offset even when replication is disabled (and
there's no replication backlog, only if there's an AOF enabled).
This way we can use this command and it's mechanisms even when replication
is disabled.
* Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK
will be appended only if there's an AOF on the replica, and already ignored on
old masters (thus backwards compatible)
* WAIT now no longer wait for the replication offset after your last command, but
rather the replication offset after your last write (or read command that caused
propagation, e.g. lazy expiry).
Unrelated changes:
* WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI)
Implementation details:
* Add an atomic var named `fsynced_reploff_pending` that's updated
(usually by the bio thread) and later copied to the main `fsynced_reploff`
variable (only if the AOF base file exists).
I.e. during the initial AOF rewrite it will not be used as the fsynced offset
since the AOF base is still missing.
* Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific)
job that will also update fsync offset the field.
* Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio
worker thread, to impose ordering on their execution. This solves a
race condition where a job could set `fsynced_reploff_pending` to a higher
value than another pending fsync job, resulting in indicating an offset
for which parts of the data have not yet actually been fsynced.
Imposing an ordering on the jobs guarantees that fsync jobs are executed
in increasing order of replication offset.
* Drain bio jobs when switching `appendfsync` to "always"
This should prevent a write race between updates to `fsynced_reploff_pending`
in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and
those done in the bio thread.
* Drain the pending fsync when starting over a new AOF to avoid race conditions
with the previous AOF offsets overriding the new one (e.g. after switching to
replicate from a new master).
* Make sure to update the fsynced offset at the end of the initial AOF rewrite.
a must in case there are no additional writes that trigger a periodic fsync,
specifically for a replica that does a full sync.
Limitations:
It is possible to write a module and a Lua script that propagate to the AOF and doesn't
propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand.
These features are incompatible with the WAITAOF command, and can result
in two bad cases. The scenario is that the user executes command that only
propagates to AOF, and then immediately
issues a WAITAOF, and there's no further writes on the replication stream after that.
1. if the the last thing that happened on the replication stream is a PING
(which increased the replication offset but won't trigger an fsync on the replica),
then the client would hang forever (will wait for an fack that the replica will never
send sine it doesn't trigger any fsyncs).
2. if the last thing that happened is a write command that got propagated properly,
then WAITAOF will be released immediately, without waiting for an fsync (since
the offset didn't change)
Refactoring:
* Plumbing to allow bio worker to handle multiple job types
This introduces infrastructure necessary to allow BIO workers to
not have a 1-1 mapping of worker to job-type. This allows in the
future to assign multiple job types to a single worker, either as
a performance/resource optimization, or as a way of enforcing
ordering between specific classes of jobs.
Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 20:26:21 +02:00
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void bioDrainWorker(int job_type);
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2012-11-22 10:08:44 +01:00
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void bioKillThreads(void);
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Reclaim page cache of RDB file (#11248)
# Background
The RDB file is usually generated and used once and seldom used again, but the content would reside in page cache until OS evicts it. A potential problem is that once the free memory exhausts, the OS have to reclaim some memory from page cache or swap anonymous page out, which may result in a jitters to the Redis service.
Supposing an exact scenario, a high-capacity machine hosts many redis instances, and we're upgrading the Redis together. The page cache in host machine increases as RDBs are generated. Once the free memory drop into low watermark(which is more likely to happen in older Linux kernel like 3.10, before [watermark_scale_factor](https://lore.kernel.org/lkml/1455813719-2395-1-git-send-email-hannes@cmpxchg.org/) is introduced, the `low watermark` is linear to `min watermark`, and there'is not too much buffer space for `kswapd` to be wake up to reclaim memory), a `direct reclaim` happens, which means the process would stall to wait for memory allocation.
# What the PR does
The PR introduces a capability to reclaim the cache when the RDB is operated. Generally there're two cases, read and write the RDB. For read it's a little messy to address the incremental reclaim, so the reclaim is done in one go in background after the load is finished to avoid blocking the work thread. For write, incremental reclaim amortizes the work of reclaim so no need to put it into background, and the peak watermark of cache can be reduced in this way.
Two cases are addresses specially, replication and restart, for both of which the cache is leveraged to speed up the processing, so the reclaim is postponed to a right time. To do this, a flag is added to`rdbSave` and `rdbLoad` to control whether the cache need to be kept, with the default value false.
# Something deserve noting
1. Though `posix_fadvise` is the POSIX standard, but only few platform support it, e.g. Linux, FreeBSD 10.0.
2. In Linux `posix_fadvise` only take effect on writeback-ed pages, so a `sync`(or `fsync`, `fdatasync`) is needed to flush the dirty page before `posix_fadvise` if we reclaim write cache.
# About test
A unit test is added to verify the effect of `posix_fadvise`.
In integration test overall cache increase is checked, as well as the cache backed by RDB as a specific TCL test is executed in isolated Github action job.
2023-02-12 15:23:29 +08:00
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void bioCreateCloseJob(int fd, int need_fsync, int need_reclaim_cache);
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Implementing the WAITAOF command (issue #10505) (#11713)
Implementing the WAITAOF functionality which would allow the user to
block until a specified number of Redises have fsynced all previous write
commands to the AOF.
Syntax: `WAITAOF <num_local> <num_replicas> <timeout>`
Response: Array containing two elements: num_local, num_replicas
num_local is always either 0 or 1 representing the local AOF on the master.
num_replicas is the number of replicas that acknowledged the a replication
offset of the last write being fsynced to the AOF.
Returns an error when called on replicas, or when called with non-zero
num_local on a master with AOF disabled, in all other cases the response
just contains number of fsync copies.
Main changes:
* Added code to keep track of replication offsets that are confirmed to have
been fsynced to disk.
* Keep advancing master_repl_offset even when replication is disabled (and
there's no replication backlog, only if there's an AOF enabled).
This way we can use this command and it's mechanisms even when replication
is disabled.
* Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK
will be appended only if there's an AOF on the replica, and already ignored on
old masters (thus backwards compatible)
* WAIT now no longer wait for the replication offset after your last command, but
rather the replication offset after your last write (or read command that caused
propagation, e.g. lazy expiry).
Unrelated changes:
* WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI)
Implementation details:
* Add an atomic var named `fsynced_reploff_pending` that's updated
(usually by the bio thread) and later copied to the main `fsynced_reploff`
variable (only if the AOF base file exists).
I.e. during the initial AOF rewrite it will not be used as the fsynced offset
since the AOF base is still missing.
* Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific)
job that will also update fsync offset the field.
* Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio
worker thread, to impose ordering on their execution. This solves a
race condition where a job could set `fsynced_reploff_pending` to a higher
value than another pending fsync job, resulting in indicating an offset
for which parts of the data have not yet actually been fsynced.
Imposing an ordering on the jobs guarantees that fsync jobs are executed
in increasing order of replication offset.
* Drain bio jobs when switching `appendfsync` to "always"
This should prevent a write race between updates to `fsynced_reploff_pending`
in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and
those done in the bio thread.
* Drain the pending fsync when starting over a new AOF to avoid race conditions
with the previous AOF offsets overriding the new one (e.g. after switching to
replicate from a new master).
* Make sure to update the fsynced offset at the end of the initial AOF rewrite.
a must in case there are no additional writes that trigger a periodic fsync,
specifically for a replica that does a full sync.
Limitations:
It is possible to write a module and a Lua script that propagate to the AOF and doesn't
propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand.
These features are incompatible with the WAITAOF command, and can result
in two bad cases. The scenario is that the user executes command that only
propagates to AOF, and then immediately
issues a WAITAOF, and there's no further writes on the replication stream after that.
1. if the the last thing that happened on the replication stream is a PING
(which increased the replication offset but won't trigger an fsync on the replica),
then the client would hang forever (will wait for an fack that the replica will never
send sine it doesn't trigger any fsyncs).
2. if the last thing that happened is a write command that got propagated properly,
then WAITAOF will be released immediately, without waiting for an fsync (since
the offset didn't change)
Refactoring:
* Plumbing to allow bio worker to handle multiple job types
This introduces infrastructure necessary to allow BIO workers to
not have a 1-1 mapping of worker to job-type. This allows in the
future to assign multiple job types to a single worker, either as
a performance/resource optimization, or as a way of enforcing
ordering between specific classes of jobs.
Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 20:26:21 +02:00
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void bioCreateCloseAofJob(int fd, long long offset, int need_reclaim_cache);
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void bioCreateFsyncJob(int fd, long long offset, int need_reclaim_cache);
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2020-12-23 19:13:12 -08:00
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void bioCreateLazyFreeJob(lazy_free_fn free_fn, int arg_count, ...);
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2011-09-13 15:59:48 +02:00
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/* Background job opcodes */
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Implementing the WAITAOF command (issue #10505) (#11713)
Implementing the WAITAOF functionality which would allow the user to
block until a specified number of Redises have fsynced all previous write
commands to the AOF.
Syntax: `WAITAOF <num_local> <num_replicas> <timeout>`
Response: Array containing two elements: num_local, num_replicas
num_local is always either 0 or 1 representing the local AOF on the master.
num_replicas is the number of replicas that acknowledged the a replication
offset of the last write being fsynced to the AOF.
Returns an error when called on replicas, or when called with non-zero
num_local on a master with AOF disabled, in all other cases the response
just contains number of fsync copies.
Main changes:
* Added code to keep track of replication offsets that are confirmed to have
been fsynced to disk.
* Keep advancing master_repl_offset even when replication is disabled (and
there's no replication backlog, only if there's an AOF enabled).
This way we can use this command and it's mechanisms even when replication
is disabled.
* Extend REPLCONF ACK to `REPLCONF ACK <ofs> FACK <ofs>`, the FACK
will be appended only if there's an AOF on the replica, and already ignored on
old masters (thus backwards compatible)
* WAIT now no longer wait for the replication offset after your last command, but
rather the replication offset after your last write (or read command that caused
propagation, e.g. lazy expiry).
Unrelated changes:
* WAIT command respects CLIENT_DENY_BLOCKING (not just CLIENT_MULTI)
Implementation details:
* Add an atomic var named `fsynced_reploff_pending` that's updated
(usually by the bio thread) and later copied to the main `fsynced_reploff`
variable (only if the AOF base file exists).
I.e. during the initial AOF rewrite it will not be used as the fsynced offset
since the AOF base is still missing.
* Replace close+fsync bio job with new BIO_CLOSE_AOF (AOF specific)
job that will also update fsync offset the field.
* Handle all AOF jobs (BIO_CLOSE_AOF, BIO_AOF_FSYNC) in the same bio
worker thread, to impose ordering on their execution. This solves a
race condition where a job could set `fsynced_reploff_pending` to a higher
value than another pending fsync job, resulting in indicating an offset
for which parts of the data have not yet actually been fsynced.
Imposing an ordering on the jobs guarantees that fsync jobs are executed
in increasing order of replication offset.
* Drain bio jobs when switching `appendfsync` to "always"
This should prevent a write race between updates to `fsynced_reploff_pending`
in the main thread (`flushAppendOnlyFile` when set to ALWAYS fsync), and
those done in the bio thread.
* Drain the pending fsync when starting over a new AOF to avoid race conditions
with the previous AOF offsets overriding the new one (e.g. after switching to
replicate from a new master).
* Make sure to update the fsynced offset at the end of the initial AOF rewrite.
a must in case there are no additional writes that trigger a periodic fsync,
specifically for a replica that does a full sync.
Limitations:
It is possible to write a module and a Lua script that propagate to the AOF and doesn't
propagate to the replication stream. see REDISMODULE_ARGV_NO_REPLICAS and luaRedisSetReplCommand.
These features are incompatible with the WAITAOF command, and can result
in two bad cases. The scenario is that the user executes command that only
propagates to AOF, and then immediately
issues a WAITAOF, and there's no further writes on the replication stream after that.
1. if the the last thing that happened on the replication stream is a PING
(which increased the replication offset but won't trigger an fsync on the replica),
then the client would hang forever (will wait for an fack that the replica will never
send sine it doesn't trigger any fsyncs).
2. if the last thing that happened is a write command that got propagated properly,
then WAITAOF will be released immediately, without waiting for an fsync (since
the offset didn't change)
Refactoring:
* Plumbing to allow bio worker to handle multiple job types
This introduces infrastructure necessary to allow BIO workers to
not have a 1-1 mapping of worker to job-type. This allows in the
future to assign multiple job types to a single worker, either as
a performance/resource optimization, or as a way of enforcing
ordering between specific classes of jobs.
Co-authored-by: Oran Agra <oran@redislabs.com>
2023-03-14 20:26:21 +02:00
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enum {
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BIO_CLOSE_FILE = 0, /* Deferred close(2) syscall. */
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BIO_AOF_FSYNC, /* Deferred AOF fsync. */
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BIO_LAZY_FREE, /* Deferred objects freeing. */
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BIO_CLOSE_AOF, /* Deferred close for AOF files. */
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BIO_NUM_OPS
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};
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2019-11-20 20:18:00 -05:00
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#endif
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