state file update blocks on frozen filesystem

Issue #493 new
Tildeslash repo owner created an issue

When the filesystem where monit writes the statefile freezes, monit blocks on state file update (write) and stops monitoring the system until the filesystem is r/w again.

We should change the statefile machinery to be non-blocking with write timeout, so monit can continue.

Comments (3)

  1. Tildeslash reporter

    tested with non-blocking I/O, doesn't solve the problem ... even if the file is opened as nonblocking or switched to non-blocking using fcntl(), if the filesystem where monit state file is placed is frozen, the write() will block.

    To freeze:

    fsfreeze -f /<fs_with_monit_state_file>

    To unfreeze:

    fsfreeze -u /<fs_with_monit_state_file>

    We can probably switch the statefile update to standalone thread, which won't stop the testing if it gets blocked by frozen filesystem.

    Workaround: place the statefile to a filesystem which cannot freeze (use "set statefile <path>").

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