Maybe it's related to recipe roller as well. https://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_ng/builds/240949 stays at "recipe_results" status for almost near 1 hour until it runs into exception.

More examples: https://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_ng/builds/240968
https://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_ng/builds/240981

-> current trooper 

My current hypothesis is that WerFault.exe window (http://1.bp.blogspot.com/-GciIoIvrPLc/Vk7gSorf0hI/AAAAAAAAAas/6C9KNgTpv5c/s1600/werfault-exe-02.png) blocks recipe engine from exiting somehow.

In all builds above webkit_tests lists "C:\Windows\SysWOW64\WerFault.exe" as one of the running processes.

I thought we disable Windows Error Reporting on bots... Looks like it isn't working. I'll try to figure out:
1) Why Error Reporting process appears.
2) Why it block recipe engine.

(Also I think it's a dup of 619742, though in 619742 webkit unit tests specifically get stuck).

Oh, this is old and hairy problem :(  crbug.com/522396 

Moving to this other bug. There's lot of info there.

Hmmm.Are you sure it's a duplicate? The old bug has been there fore a very long time. And I encountered this webkit_tests not finishing only in these few days. At the current latest builds, I couldn't find anyone ends up with a green bot as long as it's running webkit tests.

I'm still looking, but so far symptoms look consistent with 522396.

Probably something increased the frequency of WerFault.exe happening recently.

(Here's recent green build with webkit_tests https://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_ng/builds/241129)

vadimsh@: Hi, from the build link you provided, I didn't see it runs webkit_tests...It's a long build but it doesn't run webkit_tests...All those running webkit_tests end up being like this:
https://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_ng/builds/241165

In fact, if you look at the list of "Currently building", those builds that are stagnated at "recipe result" status are all those builds that run webkit tests..Wait for 1 hr and those builds will certain run into interrupted exception...

Err.. I probably copy-pasted wrong build. 

Here's a green one 1h ago: https://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_ng/builds/241135

Generally, commits are landing in third_party/WebKit, which means some builds are passing.

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> In fact, if you look at the list of "Currently building", those builds that are stagnated at "recipe result" status are all those builds that run webkit tests..Wait for 1 hr and those builds will certain run into interrupted exception...

Yes. In all of them, if you open "webkit_tests" step, you'll see (at the bottom) it lists "C:\Windows\SysWOW64\WerFault.exe -u -p 5824 -s 2368" process. This process stays after the tests and blocks buildbot from collecting step results. See  crbug.com/522396  for details.