This reverts commit 5ecf439078.
Reason for revert: the previous logic was correct.
The purpose of `-search.maxSamplesPerQuery` command-line flag is to limit the amounts of CPU resources,
which could be taken by a single query - see https://docs.victoriametrics.com/#resource-usage-limits .
VictoriaMetrics processes samples in blocks during querying - it reads the block, then unpacks it,
then filters out samples outside the selected time range. This means that it _spends CPU time_
on reading and unpacking of _all the samples_ in every block on the requested time range,
even if only a single sample per each block matches the given time range.
The previous logic was effectively limiting CPU time a single query could take.
The new logic fails limiting CPU time a single query could take in some pathological cases
when only a small fraction of samples per each requested block fit the requested time range.
This allows performing multiplication DoS-attacks by querying very narrow time ranges over historical blocks,
which tend to be full. For example, if the `-search.maxSamplesPerQuery` equals to a billion,
and the query requests a single sample out of 8K samples per each block, this means that the query
may unpack a billion of such blocks without exceeding the limit, e.g. it may unpack and process 8K*1e9=8e12 samples.
This is not what the resource usage limits were created for originally - see https://docs.victoriametrics.com/#resource-usage-limits
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5851
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6464
The limit is specified with command-line flag
`-search.maxSamplesPerQuery`.
Previously, samples might be over-counted and query can't be fixed by
reducing time range.
address https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5851
(cherry picked from commit 6e395048d3)
Signed-off-by: hagen1778 <roman@victoriametrics.com>
This reverts commit cb23685681.
Reason for revert: the "fix" may hide programming bugs related to incorrect creation of folders
before their use. This may complicate detecting and fixing such bugs in the future.
There are the following fixes for the issue https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5985 :
- To configure the OS to do not drop data from the system-wide temporary directory (aka /tmp).
- To run VictoriaMetrics with -cacheDataPath command-line flag, which points to the directory,
which cannot be removed automatically by the OS.
The case when the user accidentally deletes the directory with some files created by VictoriaMetrics
shouldn't be considered as expected, so VictoriaMetrics shouldn't try resolving this case automatically.
It is much better from operation and debuggability PoV is to crash with the clear `directory doesn't exist` error
in this case.
vmselect uses a cache folder in file system for two purposes:
1. Storing rollup cache results on shutdown;
2. Storing temporary search results from vmstorage during query executions.
It could happen that cache folder is deleted accidentally by user, or by OS
during cleanup routines. This would cause vmselect to:
1. panic on /metrics call, because `MustGetFreeSpace` will fail;
2. return query error user, as it won't be able to store temporary search results.
The changes in this commit are the following:
1. Make `MustGetFreeSpace` to try re-creating the cache folder if it is missing;
2. Make vmselect to try re-creating the cache folder if it can't persist tmp search
results.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5985
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Nikolay <nik@victoriametrics.com>
(cherry picked from commit cb23685681)
Remove temporary file before closing it in order to signal the OS that it shouldn't
store the file contents from page cache to disk when the file is closed.
Gracefully handle the case when the file cannot be removed before being closed -
in this case remove the file after closing it. This allows working on Windows.
Also remove superflouos opening of temporary file for reading - re-use already opened file handle for writing.
This is a follow-up for 9b1e002287
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4020
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/70
This case is possible after a new brsPool is allocated. The fix is to verify whether len(brsPool) >= len(brs.brs)
before trying to append a new item to brsPool and sharing its contents with brs.brs.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5733
This reduces the number of memory allocations at the cost of possible memory usage increase,
since now different metric name strings may hold references to the previous byte slice.
This is good tradeoff, since ProcessSearchQuery is called in vmselect, and vmselect isn't usually limited by memory.
This change has been extracted from https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5527
* app/vmselect: limit the number of parallel workers by 32
The change should improve performance and memory usage during query processing
on machines with big number of CPU cores. The number of parallel workers for
query processing is controlled via `-search.maxWorkersPerQuery` command-line flag.
By default, the number of workers is limited by the number of available CPU cores,
but not more than 32. The limit can be increased via `-search.maxWorkersPerQuery`.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* wip
- The `-search.maxWorkersPerQuery` command-line flag doesn't limit resource usage,
so move it from the `resource usage limits` to `troubleshooting` chapter at docs/Single-server-VictoriaMetrics.md
- Make more clear the description for the `-search.maxWorkersPerQuery` command-line flag
- Add the description of `-search.maxWorkersPerQuery` to docs/Cluster-VictoriaMetrics.md
- Limit the maximum value, which can be passed to `-search.maxWorkersPerQuery`, to GOMAXPROCS,
because bigger values may worsen query performance and increase CPU usage
- Improve the the description of the change at docs/CHANGELOG.md. Mark it as FEATURE instead of BUGFIX,
since it is closer to a feature than to a bugfix.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5087
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
- Document the change at docs/CHANGELOG.md
- Set the default value for -vmstorageUserTimeout to 3 seconds. This is much better
than the 0 value, which means that TCP connection to unreachable vmstorage could block
for up to 16 minutes.
- Document -vmstorageUserTimeout at docs/Cluster-VictoriaMetrics.md
`TCP_USER_TIMEOUT` (since Linux 2.6.37) specifies the maximum amount of
time that transmitted data may remain unacknowledged before TCP will
forcibly close the connection and return `ETIMEDOUT` to the application.
Setting a low TCP user timeout allows RPC connections quickly reroute
around unavailable storage nodes during network interruptions.
This eliminates the need in .(*T) casting for results obtained from Load()
Leave atomic.Value for map, since atomic.Pointer[map[...]...] makes double pointer to map,
because map is already a pointer type.
- Clarify docs about -replicationFactor command-line flag at vmselect
- Clarify description for -replicationFactor and -search.skipSlowReplicas command-line flags
- Fix the logic for returning responses if -search.skipSlowReplicas command-line flag
is enabled. The logic was broken in the 173ccf4333,
so it could return responses only if some of vmstorage nodes return error,
while it should return when query results are successfully collected from more than
(len(storageNodes) - replicationFactor) vmstorage nodes.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1207
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/711
* vmselect: introduce `search.skipSlowReplicas` cmd-line flag
vmselect has two logical conditions during request processing when
`-replicationFactor` cmd-line flag is set:
1. If at least `len(storageNodes) - replicationFactor` responded, it could skip
waiting for the rest of nodes to respond. This could lead to problems described
here https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1207.
2. Mark response as partial if less than `len(storageNodes) - replicationFactor` responded
without an error.
The P1 showed itself error-prone and became the main reason why
`-replicationFactor` wasn't recommended to use at vmselect level.
However, this optimization could be still very useful in situations
when there are slow and fast replicas in cluster.
But P2 remains viable and important conditionless.
Hiding P1 behind the feature-flag `search.skipSlowReplicas`
should make `-replicationFactor` flag usable again. And let users
choose whether they want P1 to be respected.
Related issues
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1207https://github.com/VictoriaMetrics/VictoriaMetrics/issues/711
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* docs: update changelog
Signed-off-by: hagen1778 <roman@victoriametrics.com>
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
- Clarify the scope of the fix at docs/CHANGELOG.md
- Handle the case when -search.maxSamplesPerSeries limit is exceeded
in the same way as the -search.maxSamplesPerQuery limit.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4472
Properly return the error to user when `-search.maxSamplesPerQuery` limit is exceeded.
Before, user could have received a partial response instead.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Callers of these functions log the returned error and then exit. The returned error already contains the path
to directory, which was failed to be created. So let's just log the error together with the call stack
inside these functions. This leaves the debuggability of the returned error at the same level
while allows simplifying the code at callers' side.
While at it, properly use MustMkdirFailIfExist instead of MustMkdirIfNotExist inside inmemoryPart.MustStoreToDisk().
It is expected that the inmemoryPart.MustStoreToDick() must fail if there is already a directory under the given path.
using `runtime.Gosched` requires acquiring global lock to check if there are any other goroutines to perform tasks. with the latest versions of runtime it can pause running goroutines automatically without requiring to call `Gosched` directly.
Updates #3966
Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>
Call runtime.Gosched() only when there is a work to steal from other workers.
Simplify the timeseriesWorker() and unpackWroker() code a bit by inlining stealTimeseriesWork() and stealUnpackWork().
This should reduce CPU usage when processing queries on systems with big number of CPU cores.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3966
