Metrics worker concurrent modification issue about honeybadger-ruby HOT 7 CLOSED

Thanks for the info, I'll look into this.

from honeybadger-ruby.

I wonder if using the Mutex class would solve the problem? http://www.ruby-doc.org/core-2.0.0/Mutex.html

from honeybadger-ruby.

A mutex on reads and writes would fix the issue, but that'd effectively only allow one request at a time. It wouldn't be terribly efficient.

from honeybadger-ruby.

Well, if this issue is only occurring when we duplicate the hash, I think we could get away with it there because it only happens every 60 seconds (when we send the metric data to the server). The duplication should happen relatively quickly, and the Mutex would prevent the race condition. Does that sounds right, or am I missing something?

from honeybadger-ruby.

This gem is also interesting, and looks similar to hamster: https://github.com/headius/thread_safe

from honeybadger-ruby.

The problem is you're reading while still writing to the hash. Putting a mutex around the read would just prevent two threads from reading at the same time . . . other threads would still be able to write. So you'd need to have the mutex around both the reads and the writes or come up with a ThreadLocal solution. Alternatively, you could push the dup from the read case to the write case, but you'd end up duping on every request. And without a mutex there, you could lose entries..

from honeybadger-ruby.

Cool, thanks for the help on this.

For posterity, it seems that the hamster gem provides thread safe constructs by making them immutable, however in our case we would still need to synchronize access to the metrics instance variable on every write. The thread_safe gem I mentioned above takes the second approach of wrapping every operation on the object in a mutex (or equivalent -- in JRuby, it uses the jruby/synchronized library, which appears to have been added to JRuby specifically for the thread_safe gem.

Since we're currently writing to the metrics hash in a single place and reading from it in a single place, I'm going to keep it simple and just add a lock in those two methods (Monitor#add_metric and Monitor#send_metrics). I'll revisit the need for an extra dependency or different approach once we further build out the metrics feature.

from honeybadger-ruby.