watchfrr: force kill daemons on restart #17163
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Today, watchfrr sends a SIGSTOP to a misbehaving daemon through frrcommon. The issue is, a stuck daemon (like in a thread starvation situation) will not honor a SIGSTOP, and watchfrr will try indefinitely to kill it. Let's not waste time and kill -9 from the get go. Signed-off-by: Tuetuopay <[email protected]>
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Note: this PR is also to start the discussion. I would definitely understand if this is not the way you want to do this, or if there are huge issues I missed with those changes. Anyways. This is becoming problematic at scale, because I've been hitting a lot of issues with bgpd becoming completely unresponsive. And bgpd unresponsive also means bgpd not handling signals. Using |
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This seems like a band-aid solution. Instead of using a "hammer" with bgp, we should be looking at the reasons why it becomes unresponsive in the first place and fix those. |
While I do agree with you that this should ultimately be fixed (we are trying to reproduce the issue in a lab), as it stands watchfrr is nigh useless because it cannot restart a failed bgpd. So yes, this is a band-aid, but the mechanism is already here. And honestly I don't want to be woken up at 4AM because the auto-heal does not work (though I've already deployed this as a quick measure). It's not a solution, but it keeps production happy. Would having two hammers be better for you? Keeping the kill -2 for e.g. 12s, and going the kill -9 route if this fails? |
Yeah. That is more reasonable, give it 12 or maybe 30 seconds? |
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Great! watchfrr has a by default 20s timeout. do you prefer I give the daemon a bit less than that (e.g. 15s), or raise the default watchfrr timeout to 35s and use the big gun after 30s? |
Today, watchfrr sends a SIGSTOP to a misbehaving daemon through frrcommon. The issue is, a stuck daemon (like in a thread starvation situation) will not honor a SIGSTOP, and watchfrr will try indefinitely to kill it.
Let's not waste time and kill -9 from the get go.