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fix(logwatchers/journald): back off when sd_journal_wait fails #1285

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fix(logwatchers/journald): back off when sd_journal_wait fails #1285

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11 changes: 10 additions & 1 deletion pkg/systemlogmonitor/logwatchers/journald/log_watcher.go
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Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,16 @@ func (j *journaldWatcher) watchLoop() {
}
// If next reaches the end, wait for waitLogTimeout.
if n == 0 {
j.journal.Wait(waitLogTimeout)
// sd_journal_wait can return immediately with a negative
// errno (e.g. -ENOSPC when inotify user instances are
// exhausted, so sd_journal_get_fd cannot create the
// inotify instance it needs). Fall back to a manual sleep
// so the loop honors waitLogTimeout instead of spinning
// at 100% CPU.
if r := j.journal.Wait(waitLogTimeout); r < 0 {

@DigitalVeer DigitalVeer Jul 8, 2026

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this logs every ~5s for as long as the condition lasts (~720/hr). would it be better to log once when it fails and once when it recovers instead?

klog.Errorf("sd_journal_wait failed (%d), backing off for %v", r, waitLogTimeout)

@DigitalVeer DigitalVeer Jul 8, 2026

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It may be worth decoding the errno:

if r := j.journal.Wait(waitLogTimeout); r < 0 {
    klog.Errorf("sd_journal_wait failed (%d: %s), backing off for %v", r, syscall.Errno(-r), waitLogTimeout)
    ...
}

if we use syscall.Errno(-r), "no space left on device" is more descriptive than -28.

time.Sleep(waitLogTimeout)
}
continue
}

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