Sudden stall at 100% CPU #858

Stebalien · 2020-03-27T00:11:50Z

Knowns:

Started happening after 7ba3222 but before 0.6.1.
The node is completely unresponsive, even to pprof.

Likely: golang/go#38070

The text was updated successfully, but these errors were encountered:

Stebalien · 2020-03-27T00:12:17Z

Suspects:

yamux. We re-enabled write coalescing in both yamux and mplex in this range of commits. We should try downgrading yamux.
Go. Yes, go itself.

Stebalien · 2020-03-27T00:14:47Z

Traces before the issue. View the trace with go tool trace ./traces/trace. View the profile with go tool pprof ./traces/profile.

traces.tar.gz

Stebalien · 2020-03-27T00:15:48Z

Stackdump: Process with stackparse

stackdump.txt

Stebalien · 2020-03-27T00:24:31Z

@alanshaw could you post the go version and linux version?

Stebalien · 2020-03-27T01:10:59Z

The go suspect:

goroutine 0 [idle]:
runtime.futex(0x152d0e8, 0x80, 0x0, 0x0, 0x0, 0x46a6f5, 0x6f5fc, 0x3b72265d, 0x7ffdee735cb8, 0x40caef, ...)
        /usr/local/go/src/runtime/sys_linux_amd64.s:567 +0x21
runtime.futexsleep(0x152d0e8, 0x0, 0xffffffffffffffff)
        /usr/local/go/src/runtime/os_linux.go:45 +0x46
runtime.notesleep(0x152d0e8)
        /usr/local/go/src/runtime/lock_futex.go:151 +0x9f
runtime.stopm()
        /usr/local/go/src/runtime/proc.go:1828 +0xc0
runtime.findrunnable(0xc00006a000, 0x0)
        /usr/local/go/src/runtime/proc.go:2360 +0xa0d
runtime.schedule()
        /usr/local/go/src/runtime/proc.go:2520 +0x2fc
runtime.park_m(0xc0008e8780)
        /usr/local/go/src/runtime/proc.go:2690 +0x9d
runtime.mcall(0x0)
        /usr/local/go/src/runtime/asm_amd64.s:318 +0x5b

and

goroutine 496872 [runnable]:
runtime.resettimer(...)
        /usr/local/go/src/runtime/time.go:488
time.resetTimer(0xc006487868, 0x19ee734323e21)
        /usr/local/go/src/runtime/time.go:223 +0x62
time.(*Timer).Reset(0xc006487860, 0x186a0, 0x3)
        /usr/local/go/src/time/sleep.go:126 +0x7d
github.com/libp2p/go-yamux.(*Session).sendLoop(0xc005e35b20, 0x0, 0x0)
        /go/pkg/mod/github.com/libp2p/[email protected]/session.go:513 +0x895
github.com/libp2p/go-yamux.(*Session).send(0xc005e35b20)
        /go/pkg/mod/github.com/libp2p/[email protected]/session.go:413 +0x2b
created by github.com/libp2p/go-yamux.newSession
        /go/pkg/mod/github.com/libp2p/[email protected]/session.go:130 +0x3d7

Clearly there is work to run, but it looks like findrunnable isn't finding anything. We may need to take a crack at this with gdb to confirm that this.

This is why the Linux version and go version matter.

Stebalien · 2020-03-27T01:44:47Z

Looking deeper, I'm seeing streams stuck reading 30 minutes in the DHT. They're supposed to be reset after 10 minutes.

alanshaw · 2020-03-27T07:15:50Z

go 1.14

I’ll check the linux version asap

See libp2p/go-libp2p#858

alanshaw · 2020-03-27T10:36:59Z

$ hostnamectl
   Static hostname: n/a
Transient hostname: gke-cluster-1-default-pool-b49ccc89-w9n3
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 224bd461662f618bdb8f842af3ce3abf
           Boot ID: 9f7917a78a30441e8a2fed11f51bde86
    Virtualization: kvm
  Operating System: Container-Optimized OS from Google
            Kernel: Linux 4.14.138+
      Architecture: x86-64

Stebalien · 2020-03-27T16:21:10Z

@alanshaw could we try upgrading libp2p and upgrading yamux: GOPROXY=direct go get github.com/libp2p/go-libp2p@fix/re-disable-write-coalescing?

alanshaw · 2020-03-27T17:27:39Z

git log 7ba322..76c1f95 --pretty=oneline
76c1f95caa7a7e22a1d971e8e186d9129ba77a74 (tag: v0.6.1) Merge pull request #846 from libp2p/chore/dep-update
7b280dd74dc58f65e312b3bdb8fbde6b857af1a9 chore: update yamux
891aeda705813f93d2d0b8108aa93e7ef141b61f Merge pull request #843 from libp2p/dependabot/go_modules/github.com/libp2p/go-libp2p-yamux-0.2.4
71e2d4ed5ba1f0b8247e668a17995bb4d2b42ddb build(deps): bump github.com/libp2p/go-libp2p-yamux from 0.2.2 to 0.2.4
463fa2a0dcbd5ee139011f36eb4975af63e05b1a Merge pull request #838 from libp2p/dependabot/go_modules/github.com/multiformats/go-multiaddr-net-0.1.3
ca57cf904e462e0977b41c7cb382c75d673778d9 build(deps): bump github.com/multiformats/go-multiaddr-net
9ad477ba8b7a369cad709790eca366e8afe2d3e0 (tag: v0.6.0) Merge pull request #836 from libp2p/feat/reliable-mock-notif
5f75aa2068f276cc5140879cda7fed1f0b131afe feat(mock): reliable notifications
4bbf43e8b2deeeb3f5db32cb94ae0286a95812b5 Merge pull request #835 from libp2p/fix/autorelay-doc
61634630e8114d4883fb1881c39554b26adbf3fa Merge pull request #833 from libp2p/dependabot/go_modules/github.com/libp2p/go-libp2p-mplex-0.2.2
8248da96b0a406501d72a8442a545eff6997e280 doc(options): fix autorelay documentation
241a61a246fab62af3341f022d1788829074fe12 build(deps): bump github.com/libp2p/go-libp2p-mplex from 0.2.1 to 0.2.2
8a52e862ee20881eb7e4c4cf6b33dd617664b873 Merge pull request #832 from libp2p/dependabot/go_modules/github.com/libp2p/go-libp2p-yamux-0.2.2
15fa3033c50088580b692871540401839a58b1f1 Merge pull request #834 from libp2p/dependabot/go_modules/github.com/libp2p/go-libp2p-peerstore-0.2.0
b5853020f816dad92542a0a03d33258ffdc0d0b5 build(deps): bump github.com/libp2p/go-libp2p-peerstore
a3bbeef22e33e1fefefdb52bc73e9c1a03a93618 build(deps): bump github.com/libp2p/go-libp2p-yamux from 0.2.1 to 0.2.2
e641f58681af49b132f38c2b7053eaea2addb0d6 Merge pull request #817 from libp2p/dependabot/go_modules/github.com/multiformats/go-multiaddr-0.2.1
34e69d491c213cd4566ee505b9adab85ff10a8e5 Merge pull request #796 from libp2p/generalize-private-network
cd4c6d3d115a7713ed6fe609c63da197c06788f1 Merge pull request #827 from libp2p/update-readme
4ccf0171045a60476b5c05d0e844fe60d3ebb3e4 Merge pull request #820 from libp2p/fix/remove-goroutine
d6d208197105b2287ff1aba14a23573490c4a62c Merge pull request #810 from libp2p/fix/relays-without-content-routing
68f9fd0e13bce74a8743fc394d54cca860b6b03c change PrivateNetwork to accept a PSK, update constructor magic
ebb9cb8af12faae59ec1cae4c8198cfea26cb422 Merge pull request #815 from Wondertan/fix/reset-error
5a6c36d346dda699f0bd99ff3b32cb9e1d23fbdd Merge pull request #826 from vasco-santos/docs/uniform
969eedc98f44ff9c362e6452dc8a842ed2ea0dc9 docs: remove note to non cancelled dev calls
b55baf18e967d8dd509c3b430b4217fa50a6a1e1 docs: remove deprecated packages
fe2c13c71b1c091293c712d6d0fef4bdfdf985f0 docs: uniform comment sentences
6cdc40418044dc96a9a90aefb0cc24faff647ffe fix: remove an unnecessary goroutine
6b1179649ff1276f10a8a6fe8b384959a281d743 build(deps): bump github.com/multiformats/go-multiaddr
5e30cdeaacdfdb1394048e6aa9668a4bfe78cb36 use of mux.ErrReset
78ca1bf57c421b79ce278075c7a311f7775f72b8 fix: can enable autorelay without content routing as long as there are static relays configured

I'm running a Hydra with e641f58681af49b132f38c2b7053eaea2addb0d6 now and stable so far...will leave it running for longer and report back.

alanshaw · 2020-03-27T17:31:43Z

@alanshaw could we try upgrading libp2p and upgrading yamux: GOPROXY=direct go get github.com/libp2p/go-libp2p@fix/re-disable-write-coalescing?

Sorry I missed this - I'll deploy this in a few hours and let you know.

Stebalien · 2020-03-27T17:47:03Z

Tell me how this test fairs first.

Stebalien · 2020-03-27T19:49:38Z

Ok, found a go bug that looks like the issue: golang/go#38070. I have a repro:

package main

import (
	"fmt"
	"time"
)

func main() {
	ticker := time.NewTicker(time.Millisecond)
	defer ticker.Stop()
	exit := make(chan struct{})
	running := 0
	for {
		for i := 0; i < 100; i++ {
			running++
			go func() {
				timer := time.NewTimer(1 * time.Microsecond)
				for {
					for k := 0; k < 100; k++ {
						timer.Reset(100 * time.Microsecond)
					}
					select {
					case <-timer.C:
					case exit <- struct{}{}:
						return
					}
				}
			}()
			if running > 4000 {
				<-ticker.C
				select {
				case <-exit:
					running--
				default:
				}
			}
		}
		fmt.Printf("running: %d\n", running)
	}
}

This works on go 1.13 but grinds to a halt on go 1.14.1 (even with the preemptive scheduler disabled).

Stebalien · 2020-03-27T21:12:59Z

Issue submitted upstream: golang/go#38119.

It looks like the code above "works" on the latest master (which has fixed a timer reset deadlock). However, it still doesn't work well.

This reverts commit c88a690. Unfortunately, go 1.14's new scheduler and timer changes have a few bugs that need to be ironed out before it's ready for production use. See: * libp2p/go-libp2p#858 * golang/go#38119

alanshaw · 2020-03-27T23:15:36Z

Still stable running e641f58681af49b132f38c2b7053eaea2addb0d6

Stebalien · 2020-03-27T23:51:01Z

Yeah, that sounds like the write coalescing is causing it. Try the latest go-lib2p release with the patches I've posted.

RubenKelevra · 2020-03-30T18:41:31Z

might be related or not.

There's a complete debug log attached from the start until it freezes plus the stack trace after kill (if this helps?)

ipfs/kubo#7049

Stebalien · 2020-03-30T20:03:02Z

It's not related.

Stebalien · 2020-05-13T00:25:49Z

Resolved by updating to go 1.14.2.

Stebalien added the kind/bug A bug in existing code (including security flaws) label Mar 27, 2020

alanshaw added a commit to libp2p/hydra-booster that referenced this issue Mar 27, 2020

chore: downgrade to last known good libp2p

87e8152

See libp2p/go-libp2p#858

Stebalien mentioned this issue Mar 27, 2020

runtime: starvation with frequent timer resets golang/go#38119

Closed

Stebalien mentioned this issue Mar 27, 2020

Revert "use Go 1.14's embedded interfaces, update CIs" quic-go/quic-go#2446

Closed

Stebalien mentioned this issue Mar 29, 2020

http gateway freezes: no response code will be returned ipfs/kubo#7032

Closed

requilence mentioned this issue Apr 6, 2020

go: update to 1.14 textileio/go-threads#303

Merged

Stebalien closed this as completed May 13, 2020

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Sudden stall at 100% CPU #858

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Sudden stall at 100% CPU #858

Sudden stall at 100% CPU #858

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