Bug 313710 – REGRESSION(311577@main): [GTK][GStreamer][Rice] WebKitNetworkProcess is using massive amounts of CPU and spanning several threads named webrtc-rice-XX

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Carlos Alberto Lopez Perez]

The GTK test bot is under unusual pressure lately, tests are exiting early randomly due to timeouts.

The cause seems to be that sometimes WebKitNetworkProcess starts using lot of CPU with several threads named "webrtc-rice-XX"

This happens randomly on some layout tests, so it is not easy to reproduce running one test alone.

The best way I found to reproduce this is:

1. Run:
Tools/Scripts/run-webkit-tests --no-show-results --no-new-test-results --no-retry-failures --no-sample-on-timeout --no-build --results-directory layout-test-results --debug-rwt-logging --release --gtk --no-timeout -f webrtc

2. On another tab check with htop the CPU usage of those WebKitNetworkProcess (you can enable to display thread names via F2->Display Options->Show custom thread names) and you will see a lot of webrtc-rice-XX thread using lot of CPU.

[Carlos Alberto Lopez Perez]

Note: passing --no-timeout to run-webkit-tests is needed so the tool doesn't kill WTR. The idea is that those tests should not enter into that very long (endless?) busy loop even when passing --no-timeout

[Carlos Alberto Lopez Perez]

I have bisected this, this is caused by 311577@main

Confirmed by:
 - Checkout 311576@main and run test 1, wait for run-webkit-tests to print lines, then wait 1 minute more and you see only one WebKitWebProcess spinning CPU, which seems unrelated to this bug
 - Checkout 311577@main and run test 1, wait for run-webkit-tests to print lines, then wait 1 minute more and you see the previous WebKitWebProcess spinning CPU but a lot more WebKitNetworkProcess spinning even more CPU.

This is a "top" snapshot around 2 minutes later than run-webkit-tests stopped printing lines
Check how there is even a WebKitNetworkProcess with more than 20 minutes of CPU time used burning through several cores (636% CPU usage).
That doesn't happen before 311577@main

Note: I also tested to revert in the SDK https://github.com/Igalia/webkit-container-sdk/commit/c228acd but the issue keeps happening with librice v0.3.0

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                                                                                                                
1561064 clopez    20   0   86.0g 195388  67096 S 636.0   0.1  20:55.51 WebKitNetworkPr                                                                                                        
1560495 clopez    20   0   72.3g  95576  67352 S 147.4   0.1   4:47.17 WebKitNetworkPr                                                                                                        
1560676 clopez    20   0   71.9g  95596  66452 S 144.7   0.1   4:25.84 WebKitNetworkPr                                                                                                        
1560835 clopez    20   0   72.7g  97464  67248 S 127.2   0.1   3:39.79 WebKitNetworkPr                                                                                                        
1560862 clopez    20   0   71.8g  95340  66444 S 121.9   0.1   3:49.37 WebKitNetworkPr                                                                                                        
1560500 clopez    20   0   72.4g 100792  69296 S 103.5   0.1   3:50.74 WebKitNetworkPr                                                                                                        
1560891 clopez    20   0   71.4g  95452  67348 S  96.5   0.1   2:38.17 WebKitNetworkPr                                                                                                        
1561016 clopez    20   0   71.5g  95536  67400 S  96.5   0.1   3:00.53 WebKitNetworkPr                                                                                                        
1560900 clopez    20   0   71.6g  95228  66436 S  93.9   0.1   2:46.44 WebKitNetworkPr                                                                                                        
1560861 clopez    20   0   71.3g  95080  66328 S  88.6   0.1   2:40.04 WebKitNetworkPr                                                                                                        
1560694 clopez    20   0   72.1g  95272  66432 S  83.3   0.1   2:48.20 WebKitNetworkPr                                                                                                        
1560923 clopez    20   0   72.0g  95504  66508 S  78.1   0.1   3:09.31 WebKitNetworkPr                                                                                                        
1560875 clopez    20   0   71.7g  95884  66640 S  60.5   0.1   3:15.21 WebKitNetworkPr                                                                                                        
1560839 clopez    20   0   71.4g  95408  67376 S  57.0   0.1   2:13.37 WebKitNetworkPr                                                                                                        
1560897 clopez    20   0   71.0g  95248  66472 S  57.0   0.1   1:32.37 WebKitNetworkPr                                                                                                        
1561380 clopez    20   0   81.5g 632108 283636 R  42.1   0.5   1:41.94 WebKitWebProces                                                                                                        
1560725 clopez    20   0   71.1g  95328  66644 S  37.7   0.1   1:29.10 WebKitNetworkPr                                                                                                        
1560951 clopez    20   0   71.1g  95348  66636 S  36.8   0.1   2:09.71 WebKitNetworkPr                                                                                                        
1560745 clopez    20   0   71.1g  95040  67180 S  31.6   0.1   0:42.01 WebKitNetworkPr                                                                                                        
1560902 clopez    20   0   71.0g  94756  66320 S  31.6   0.1   1:39.89 WebKitNetworkPr                                                                                                        
1560873 clopez    20   0   71.5g  95416  66500 S  28.1   0.1   0:43.34 WebKitNetworkPr                                                                                                        
1561033 clopez    20   0   70.9g  95140  67172 S  27.2   0.1   0:48.47 WebKitNetworkPr                                                                                                        
1560724 clopez    20   0   71.0g  95168  66404 S  23.7   0.1   0:49.81 WebKitNetworkPr

[Philippe Normand]

Pull request: https://github.com/WebKit/WebKit/pull/63960

[Philippe Normand]

I think the recv GSource blocks on TCP sockets polling, or maybe there's a bug in rice-io. I don't have time to investigate this further now, so we went for a short-term workaround, to make bots happy...

[EWS]

Committed 312352@main (5ef5c9f38896): <https://commits.webkit.org/312352@main>

Reviewed commits have been landed. Closing PR #63960 and removing active labels.

[Philippe Normand]

We'd need a proper patch instead of a workaround. Re-opening.

[Philippe Normand]

Pull request: https://github.com/WebKit/WebKit/pull/64664

[EWS]

Committed 313309@main (ecec9b6009d9): <https://commits.webkit.org/313309@main>

Reviewed commits have been landed. Closing PR #64664 and removing active labels.