Merge #116633 #116670

116633: server: dynamically increase compaction concurrency during downloads r=dt a=dt Early in an online restore, a workload may not be able to utilize all CPU due to the high latency of accessing still-remote data meaning that many or most queries spend most of their time waiting rather than executing. During this phase, increasing the compaciton concurrency can expedite getting data downloaded, to reduce that latency and improve the workload performance. However later in the download phase, when more of the most accessed data has been downloaded, the workload itself may be able to execute fast enough that it requires the majority of available CPU. At this point, excessive CPU usage by download compactions will actually negatively impact the workload performance. Thus it is desirable to maximize compaction concurrency when CPU is available but reduce it when becomes scarce. This change introduces an additional goroutine to the download call that monitors CPU usage and adjusts compaction concurrency up and down based on the CPU usage being below 70% or above 80% respectively. Release note: none. Epic: none. 116670: go.mod: bump Pebble to 48b54c29d8fe r=RaduBerinde a=itsbilal cockroachdb/pebble@48b54c29 sstable: fix incorrect range key mask in virtualLast() Informs #116330. Release note: None. Epic: none Co-authored-by: David Taylor <tinystatemachine@gmail.com> Co-authored-by: Bilal Akhtar <bilal@cockroachlabs.com>
cockroachdb · Dec 18, 2023 · 6fae6a7 · 6fae6a7
3 parents fb2e117 + acff1f2 + c623233
commit 6fae6a7
Show file tree

Hide file tree

Showing 7 changed files with 92 additions and 8 deletions.
diff --git a/DEPS.bzl b/DEPS.bzl
@@ -1613,10 +1613,10 @@ def go_deps():
  patches = [
  "@com_github_cockroachdb_cockroach//build/patches:com_github_cockroachdb_pebble.patch",
  ],
- sha256 = "c63d15d21281f795e2cd016da02fdfa7a64a3365909fabd8d5581636af4fe7e0",
- strip_prefix = "github.com/cockroachdb/pebble@v0.0.0-20231214172447-ab4952c5f87b",
+ sha256 = "1878bb40f322c5c93bb7db26b6287219eb56507fc59b82292fcd4d2187639a16",
+ strip_prefix = "github.com/cockroachdb/pebble@v0.0.0-20231218155426-48b54c29d8fe",
  urls = [
- "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20231214172447-ab4952c5f87b.zip",
+ "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20231218155426-48b54c29d8fe.zip",
  ],
  )
  go_repository(

diff --git a/build/bazelutil/distdir_files.bzl b/build/bazelutil/distdir_files.bzl
@@ -322,7 +322,7 @@ DISTDIR_FILES = {
  "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/gostdlib/com_github_cockroachdb_gostdlib-v1.19.0.zip": "c4d516bcfe8c07b6fc09b8a9a07a95065b36c2855627cb3514e40c98f872b69e",
  "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/logtags/com_github_cockroachdb_logtags-v0.0.0-20230118201751-21c54148d20b.zip": "ca7776f47e5fecb4c495490a679036bfc29d95bd7625290cfdb9abb0baf97476",
  "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/metamorphic/com_github_cockroachdb_metamorphic-v0.0.0-20231108215700-4ba948b56895.zip": "28c8cf42192951b69378cf537be5a9a43f2aeb35542908cc4fe5f689505853ea",
- "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20231214172447-ab4952c5f87b.zip": "c63d15d21281f795e2cd016da02fdfa7a64a3365909fabd8d5581636af4fe7e0",
+ "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20231218155426-48b54c29d8fe.zip": "1878bb40f322c5c93bb7db26b6287219eb56507fc59b82292fcd4d2187639a16",
  "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/redact/com_github_cockroachdb_redact-v1.1.5.zip": "11b30528eb0dafc8bc1a5ba39d81277c257cbe6946a7564402f588357c164560",
  "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/returncheck/com_github_cockroachdb_returncheck-v0.0.0-20200612231554-92cdbca611dd.zip": "ce92ba4352deec995b1f2eecf16eba7f5d51f5aa245a1c362dfe24c83d31f82b",
  "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/stress/com_github_cockroachdb_stress-v0.0.0-20220803192808-1806698b1b7b.zip": "3fda531795c600daf25532a4f98be2a1335cd1e5e182c72789bca79f5f69fcc1",

diff --git a/go.mod b/go.mod
@@ -113,7 +113,7 @@ require (
  github.com/cockroachdb/go-test-teamcity v0.0.0-20191211140407-cff980ad0a55
  github.com/cockroachdb/gostdlib v1.19.0
  github.com/cockroachdb/logtags v0.0.0-20230118201751-21c54148d20b
- github.com/cockroachdb/pebble v0.0.0-20231214172447-ab4952c5f87b
+ github.com/cockroachdb/pebble v0.0.0-20231218155426-48b54c29d8fe
  github.com/cockroachdb/redact v1.1.5
  github.com/cockroachdb/returncheck v0.0.0-20200612231554-92cdbca611dd
  github.com/cockroachdb/stress v0.0.0-20220803192808-1806698b1b7b

diff --git a/go.sum b/go.sum
@@ -493,8 +493,8 @@ github.com/cockroachdb/logtags v0.0.0-20230118201751-21c54148d20b h1:r6VH0faHjZe
 github.com/cockroachdb/logtags v0.0.0-20230118201751-21c54148d20b/go.mod h1:Vz9DsVWQQhf3vs21MhPMZpMGSht7O/2vFW2xusFUVOs=
 github.com/cockroachdb/metamorphic v0.0.0-20231108215700-4ba948b56895 h1:XANOgPYtvELQ/h4IrmPAohXqe2pWA8Bwhejr3VQoZsA=
 github.com/cockroachdb/metamorphic v0.0.0-20231108215700-4ba948b56895/go.mod h1:aPd7gM9ov9M8v32Yy5NJrDyOcD8z642dqs+F0CeNXfA=
-github.com/cockroachdb/pebble v0.0.0-20231214172447-ab4952c5f87b h1:r3BhKev3k3GhdEGl9PMSO1MBZu5P1D+JXAcXI4O21UY=
-github.com/cockroachdb/pebble v0.0.0-20231214172447-ab4952c5f87b/go.mod h1:BHuaMa/lK7fUe75BlsteiiTu8ptIG+qSAuDtGMArP18=
+github.com/cockroachdb/pebble v0.0.0-20231218155426-48b54c29d8fe h1:ZBhPcgWjnfy2PFWlvPlcOXAfAQqOIdpfksijpKiMWcc=
+github.com/cockroachdb/pebble v0.0.0-20231218155426-48b54c29d8fe/go.mod h1:BHuaMa/lK7fUe75BlsteiiTu8ptIG+qSAuDtGMArP18=
 github.com/cockroachdb/redact v1.1.3/go.mod h1:BVNblN9mBWFyMyqK1k3AAiSxhvhfK2oOZZ2lK+dpvRg=
 github.com/cockroachdb/redact v1.1.5 h1:u1PMllDkdFfPWaNGMyLD1+so+aq3uUItthCFqzwPJ30=
 github.com/cockroachdb/redact v1.1.5/go.mod h1:BVNblN9mBWFyMyqK1k3AAiSxhvhfK2oOZZ2lK+dpvRg=

diff --git a/pkg/server/span_download.go b/pkg/server/span_download.go
@@ -12,13 +12,15 @@ package server
 
 import (
  "context"
+ "time"
 
  "github.com/cockroachdb/cockroach/pkg/kv/kvserver"
  "github.com/cockroachdb/cockroach/pkg/roachpb"
  "github.com/cockroachdb/cockroach/pkg/server/authserver"
  "github.com/cockroachdb/cockroach/pkg/server/serverpb"
  "github.com/cockroachdb/cockroach/pkg/server/srverrors"
  "github.com/cockroachdb/cockroach/pkg/util/ctxgroup"
+ "github.com/cockroachdb/cockroach/pkg/util/log"
  "github.com/cockroachdb/errors"
  "google.golang.org/grpc/codes"
  "google.golang.org/grpc/status"
@@ -101,17 +103,80 @@ func (s *systemStatusServer) localDownloadSpan(
  return nil
  })
 
+ const downloadWaiters = 16
+ downloadersDone := make(chan struct{}, downloadWaiters)
+
  downloader := func(ctx context.Context) error {
  for sp := range spanCh {
  if err := store.TODOEngine().Download(ctx, sp); err != nil {
  return err
  }
  }
+ downloadersDone <- struct{}{}
  return nil
  }
- for i := 0; i < 4; i++ {
+
+ for i := 0; i < downloadWaiters; i++ {
  grp.GoCtx(downloader)
  }
+
+ grp.GoCtx(func(ctx context.Context) error {
+ var added int64
+ // Remove any additional concurrency we've added when we exit.
+ //
+ // TODO(dt,radu): Ideally we'd adjust a separate limit that applies only
+ // to download compactions, so that this does not fight with manual calls
+ // to SetConcurrentCompactions.
+ defer func() {
+ if added != 0 {
+ adjusted := store.TODOEngine().AdjustCompactionConcurrency(-added)
+ log.Infof(ctx, "downloads complete; reset compaction concurrency to %d", adjusted)
+ }
+ }()
+
+ const maxAddedConcurrency, lowCPU, highCPU, initialIncrease = 16, 0.65, 0.8, 8
+
+ // Begin by bumping up the concurrency by 8, then start watching the CPU
+ // usage and adjusting up or down based on CPU until downloading finishes.
+ store.TODOEngine().AdjustCompactionConcurrency(initialIncrease)
+ added += initialIncrease
+
+ t := time.NewTicker(time.Second * 15)
+ defer t.Stop()
+ ctxDone := ctx.Done()
+
+ var waitersExited int
+ for {
+ select {
+ case <-ctxDone:
+ return ctx.Err()
+ case <-downloadersDone:
+ waitersExited++
+ // Return and stop managing added concurrency if the workers are done.
+ if waitersExited >= downloadWaiters {
+ return nil
+ }
+ case <-t.C:
+ cpu := s.sqlServer.cfg.RuntimeStatSampler.GetCPUCombinedPercentNorm()
+ if cpu > highCPU && added > 0 {
+ // If CPU is high and we have added any additional concurrency, we
+ // should reduce our added concurrency to make sure CPU is available
+ // for the execution of foreground traffic.
+ adjusted := store.TODOEngine().AdjustCompactionConcurrency(-1)
+ added--
+ log.Infof(ctx, "decreasing additional compaction concurrency to %d (%d total) due cpu usage %.0f%% > %.0f%%", added, adjusted, cpu*100, highCPU*100)
+ } else if cpu < lowCPU {
+ // If CPU is low, we should use it to do additional downloading.
+ if added < maxAddedConcurrency {
+ adjusted := store.TODOEngine().AdjustCompactionConcurrency(1)
+ added++
+ log.Infof(ctx, "increasing additional compaction concurrency to %d (%d total) due cpu usage %.0f%% < %.0f%%", added, adjusted, cpu*100, lowCPU*100)
+ }
+ }
+ }
+ }
+ })
+
  return grp.Wait()
  })
 }
diff --git a/pkg/storage/engine.go b/pkg/storage/engine.go
@@ -1086,6 +1086,10 @@ type Engine interface {
  // concurrency. It returns the previous compaction concurrency.
  SetCompactionConcurrency(n uint64) uint64
 
+ // AdjustCompactionConcurrency adjusts the compaction concurrency up or down by
+ // the passed delta, down to a minimum of 1.
+ AdjustCompactionConcurrency(delta int64) uint64
+
  // SetStoreID informs the engine of the store ID, once it is known.
  // Used to show the store ID in logs and to initialize the shared object
  // creator ID (if shared object storage is configured).

diff --git a/pkg/storage/pebble.go b/pkg/storage/pebble.go
@@ -930,6 +930,21 @@ func (p *Pebble) SetCompactionConcurrency(n uint64) uint64 {
  return prevConcurrency
 }
 
+// AdjustCompactionConcurrency adjusts the compaction concurrency up or down by
+// the passed delta, down to a minimum of 1.
+func (p *Pebble) AdjustCompactionConcurrency(delta int64) uint64 {
+ for {
+ current := atomic.LoadUint64(&p.atomic.compactionConcurrency)
+ adjusted := int64(current) + delta
+ if adjusted < 1 {
+ adjusted = 1
+ }
+ if atomic.CompareAndSwapUint64(&p.atomic.compactionConcurrency, current, uint64(adjusted)) {
+ return uint64(adjusted)
+ }
+ }
+}
+
 // SetStoreID adds the store id to pebble logs.
 func (p *Pebble) SetStoreID(ctx context.Context, storeID int32) error {
  if p == nil {