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nmt: Fix wait_for_bootup race with a following heartbeat - #681
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SahilRajputdotexe wants to merge 1 commit into
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wait_for_bootup() looked at _state_received after being notified, but a heartbeat handled before the waiting thread got to run had already overwritten the boot-up value, so the boot-up was missed and the call timed out. Remember the boot-up in its own flag and wait on that with wait_for(). Fixes canopen-python#560
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Fixes #560.
wait_for_bootup()checks_state_receivedafter it has been notified. If a heartbeat is handled before the waiting thread gets to run,_state_receivedhas already been overwritten with the new state, so the boot-up is missed and the call times out. That matches the log in the issue, where the boot-up is followed by a heartbeat within a millisecond. Moving the check inside the lock doesn't help, because the overwrite happens before the waiter gets the lock back.This keeps the boot-up in a separate flag that later heartbeats don't touch, and waits on it with
Condition.wait_for().The new test delivers a boot-up and a heartbeat while holding the condition lock, so the waiter can only run after both. It times out on master and passes with the change.
One small difference: the timeout is now exactly the value passed in. The old loop could wait about 0.1 s longer.