*: spans that are never explicitly Finish()-ed #58721

irfansharif · 2021-01-11T20:39:12Z

Consider the following two examples (there may be others, will need to audit more thoroughly):

Lines 633 to 639 in 91a0898

    
           var stmtThresholdSpan *tracing.Span 
        
           alreadyRecording := ex.transitionCtx.sessionTracing.Enabled() 
        
           stmtTraceThreshold := traceStmtThreshold.Get(&ex.planner.execCfg.Settings.SV) 
        
           if !alreadyRecording && stmtTraceThreshold > 0 { 
        
           	ctx, stmtThresholdSpan = createRootOrChildSpan(ctx, "trace-stmt-threshold", ex.transitionCtx.tracer) 
        
           	stmtThresholdSpan.SetVerbose(true) 
        
           }

cockroach/pkg/sql/colflow/vectorized_flow.go

Line 949 in 91a0898

ctx, span := tracing.ChildSpanRemote(ctx, "")

The created spans are never explicitly Finish()-ed. This may pose to be a problem with always-on tracing (#55592), where un-Finish()-ed spans take up room in an in-memory registry of active spans (#58490). This is a tracking issue to refer to as we fix these.

blathers-crl · 2021-01-11T20:39:14Z

Hi @irfansharif, please add a C-ategory label to your issue. Check out the label system docs.

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tbg · 2021-01-11T21:01:13Z

I'm not sure they aren't explicitly finished, but it's possible. In some of the SQL code it isn't obvious when the spans are closed as they are tied to the connection. That said - I'd be surprised if there weren't any leaks. We should be able to find them easily after @angelapwen's starter project #55733.

This is follow-up work from cockroachdb#58712, where we measured the overhead for always-on tracing and found it to be minimal/acceptable. Lets switch this on by default to shake the implications of doing so. We can reasonably expect two kinds of fallout: 1. Unexpected blow up in memory usage due to resource leakage (which is a can be problem now that we're always maintaining open spans in an internal registry, see cockroachdb#58721) 2. Performance degradataion due to tracing overhead per-request (something cockroachdb#58712) was spot checking for. For 1 we'll introduce a future test in a separate PR. For 2, we'll monitor roachperf over the next few weeks. --- Also moved some of the documentation for the cluster setting into a comment form above. Looking at what's rendered in our other cluster settings (`SHOW ALL CLUSTER SETTINGS`), we default to a very pity, unwrapped description. Release note: None

With always-on tracing, we're maintaining in-memory registry of active spans (cockroachdb#58490). Spans are added and removed from this registry when they're Start()-ed and Finish()-ed. Spans that not explicitly finished (typically using `defer sp.Finish()`) are now a resource-leak, as they take up room in the registry. We'll want to find instances of this leak as soon as they crop up. To that end we add a check in our TestCluster.Stop codepaths that asserts against the registry being empty. This should give us wide coverage given it's usage throughout. We expect this change to capture the cases described in cockroachdb#58721. --- This check is currently failing, given we're actually leaking spans in `txnState.resetForNewSQLTxn`. Fixing that doesn't look simple, it ties into questions around draining SQL and rolling back open txns. Release note: None

This is follow-up work from cockroachdb#58712, where we measured the overhead for always-on tracing and found it to be minimal/acceptable. Lets switch this on by default to shake the implications of doing so. We can reasonably expect two kinds of fallout: (1) Unexpected blow up in memory usage due to resource leakage (which is a can be problem now that we're always maintaining open spans in an internal registry, see cockroachdb#58721) (2) Performance degradataion due to tracing overhead per-request (something cockroachdb#58712) was spot checking for. For (1) we'll introduce a future test in a separate PR. For (2), we'll monitor roachperf over the next few weeks. --- Also moved some of the documentation for the cluster setting into a comment form above. Looking at what's rendered in our other cluster settings (`SHOW ALL CLUSTER SETTINGS`), we default to a very pithy, unwrapped description. Release note: None

With always-on tracing, we're maintaining in-memory registry of active spans (cockroachdb#58490). Spans are added and removed from this registry when they're `Start()`-ed and `Finish()`-ed. Spans that not explicitly finished (typically using `defer sp.Finish()`) are now a resource-leak, as they take up room in the registry. We'll want to find instances of this leak as soon as they crop up[*]. To that end we add a check in our `TestCluster.Stop` codepaths that asserts against the registry being empty. This should give us wide coverage given it's usage throughout. We expect this change to capture the cases described in cockroachdb#58721. --- [*] For known issues like `txnState.resetForNewSQLTxn`, we'll temporarily introduce a `WithBypassRegistry` option. Fixing that doesn't look simple, it ties into questions around draining SQL and rolling back open txns. Release note: None

58897: tracing: enable always-on tracing by default r=irfansharif a=irfansharif This is follow-up work from #58712, where we measured the overhead for always-on tracing and found it to be minimal/acceptable. Lets switch this on by default to shake the implications of doing so. We can reasonably expect two kinds of fallout: 1. Unexpected blow up in memory usage due to resource leakage (which is a can be problem now that we're always maintaining open spans in an internal registry, see #58721) 2. Performance degradataion due to tracing overhead per-request (something #58712) was spot checking for. For 1 we'll introduce a future test in a separate PR. For 2, we'll monitor roachperf over the next few weeks. --- Also moved some of the documentation for the cluster setting into a comment form above. Looking at what's rendered in our other cluster settings (`SHOW ALL CLUSTER SETTINGS`), we default to a very pity, unwrapped description. Release note: None 58974: opt: suppress logs in benchmarks r=rytaft a=mgartner As of #57134 passing `-logtostderr=false` as a `TESTFLAG` in benchmarks errs: `flag provided but not defined: -logtostderr`. The preferred method for suppressing logs in tests and benchmarks to is add `defer log.Scope(t).Close(t)` to the top of the test/benchmark (see #57979). This commit uses this new method to suppress logs in optimizer benchmarks. Release note: None 59009: kv/batcheval: only expose immutable range state to commands r=nvanbenschoten a=nvanbenschoten The DeclareKeysFunc has always included a full RangeDescriptor, but it has never been clear which fields in this descriptor are safe to use and which are not when declaring keys for a request. The concern is that any property of the RangeDescriptor that is not immutable may change between the time that a request declares its keys to latch and the time that it evaluates, so any assumptions based on these mutable fields may not hold. The quintessential example of a property of a Range that is not immutable is its end key. It would be incorrect to declare keys between a Range's start key and its current end key as a means of latching the entire range, because a merge of a right-hand neighbor could complete in between the time that a request declares its keys and the time that it evaluates. This could lead to a violation of the mutual exclusion that the command was expecting to have. This commit makes these kinds of mistakes impossible to make by putting the RangeDescriptor behind an interface that only exposes the properties of a Range that cannot change across a Range's lifetime. 59099: kvserver: fix rangelog event logging for non-voter additions r=aayushshah15 a=aayushshah15 Before this patch, we were incorrectly logging non-voter additions as removals. Release note: None 59142: sql: fix indentation in information_schema.columns schema r=otan a=arulajmani Reviewable lied to me. Release note: None Co-authored-by: irfan sharif <irfanmahmoudsharif@gmail.com> Co-authored-by: Marcus Gartner <marcus@cockroachlabs.com> Co-authored-by: Nathan VanBenschoten <nvanbenschoten@gmail.com> Co-authored-by: Aayush Shah <aayush.shah15@gmail.com> Co-authored-by: arulajmani <arulajmani@gmail.com>

56812: kvserver: replace multiTestContext with TestCluster in client_raft_test r=lunevalex a=lunevalex Makes progress on #8299 Fixes #40351 Fixes #57560 Fixes #57537 multiTestContext is a legacy construct that is deprecated in favor of running tests via TestCluster. This is one PR out of many to remove the usage of multiTestContext in the client_raft test cases. This does not remove all the uses of mtc, just the simple ones. Leaving the more complex uses cases for a later PR. With this switch we can also clean up some TestingKnobs and TestServer interfaces. - DisablePeriodicGossips flag is removed, it does not work with TestCluster and is no longer used - DontPreventUseOfOldLeaseOnStart flag is removed, it did not work consistently in TestCluster. This flag tries to leave the Lease on the same node after a restart, but CRDB makes no such guarantees in the real world and artificially testing it does not prove anything. The affected tests were re-worked to not rely on this condition and can deal with a lease holder moving on a restart. - GetRaftLeader is ported from multiTestContext to TestCluster Release note: None 58265: sql: fix substring(byte[]) to treat input as raw bytes without escaping r=solongordon a=rafiss fixes #57367 Release note (bug fix): The substring function on byte arrays would treat its input as unicode code points, which would cause the wrong bytes to be returned. Now it only operates on the raw bytes. Release note (bug fix): The substring(byte[]) functions were not able to interpret bytes that had the `\` character since it was treating it as the beginning of an escape sequence. This is now fixed. 58902: tracing,testutils: detect span leaks r=irfansharif a=irfansharif With always-on tracing, we're maintaining in-memory registry of active spans (#58490). Spans are added and removed from this registry when they're Start()-ed and Finish()-ed. Spans that not explicitly finished (typically using `defer sp.Finish()`) are now a resource-leak, as they take up room in the registry. We'll want to find instances of this leak as soon as they crop up. To that end we add a check in our TestCluster.Stop codepaths that asserts against the registry being empty. This should give us wide coverage given it's usage throughout. We expect this change to capture the cases described in #58721. --- This check is currently failing, given we're actually leaking spans in `txnState.resetForNewSQLTxn`. Fixing that doesn't look simple, it ties into questions around draining SQL and rolling back open txns. Release note: None 59049: sql: implement alter sequence/view owner r=arulajmani a=RichardJCai Resolves #57965 Release note (sql change): Add support for ALTER VIEW/SEQUENCE OWNER TO commands. 59055: colexec: fix external aggregator fallback and bool agg functions reset r=yuzefovich a=yuzefovich Previously, `reset` method of the ordered aggregator would always set the flag to reset the internal batch to `true`. However, that batch is only allocated when `Next` is called at least once with a non-zero batch coming from the input, which is not the case when the fallback to the disk-backed strategy occurs in the external aggregator (there, we call `reset` before we use the operator every time). This would lead to a nil pointer exception, and it is now fixed. Our unit tests didn't catch it because we forgot to set the forced number of repartitions which is now also fixed. This also revealed a bug with resetting of `bool_and` and `bool_or` aggregates - we forgot to reset whether they have seen a non-null value or not. Fixes: #59043. Release note: None (no stable release with these bugs) Co-authored-by: Alex Lunev <alexl@cockroachlabs.com> Co-authored-by: Rafi Shamim <rafi@cockroachlabs.com> Co-authored-by: irfan sharif <irfanmahmoudsharif@gmail.com> Co-authored-by: richardjcai <caioftherichard@gmail.com> Co-authored-by: Yahor Yuzefovich <yahor@cockroachlabs.com>

tbg · 2021-01-20T13:58:00Z

#34313 is related. @irfansharif is fixing these (SQL) spans on our plate? I would have assumed SQL execution.

asubiotto · 2021-03-02T16:55:18Z

Is this different from #59315?

irfansharif · 2021-03-02T17:15:44Z

#59315 should be the last of it I think. The only other issue I'm aware of was #61279, but there's a PR out there already. I'll close it out.

irfansharif added A-tracing Relating to tracing in CockroachDB. A-kv-observability labels Jan 11, 2021

yuzefovich mentioned this issue Jan 11, 2021

colflow: finish spans created by the outboxes #58741

Closed

irfansharif mentioned this issue Jan 12, 2021

tracing: enable always-on tracing by default #58897

Merged

irfansharif mentioned this issue Jan 13, 2021

tracing,testutils: detect span leaks #58902

Merged

tbg assigned asubiotto Feb 24, 2021

irfansharif closed this as completed Mar 2, 2021

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*: spans that are never explicitly Finish()-ed #58721

*: spans that are never explicitly Finish()-ed #58721

irfansharif commented Jan 11, 2021 •

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blathers-crl bot commented Jan 11, 2021

tbg commented Jan 11, 2021

tbg commented Jan 20, 2021

asubiotto commented Mar 2, 2021

irfansharif commented Mar 2, 2021

*: spans that are never explicitly Finish()-ed #58721

*: spans that are never explicitly Finish()-ed #58721

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tbg commented Jan 11, 2021

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irfansharif commented Jan 11, 2021 •

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