Commit Graph

106 Commits (b46d9f30bbec40931f476358b3428582f91ac0c6)

Author SHA1 Message Date
Mike Lang bcdb268ce8 Also need to replace locks on the counter float values to prevent deadlocks
See comment for full details
6 years ago
Mike Lang 10cca18922 Fix a deadlock due to signal interactions with prometheus client
The prometheus client uses a threading.Lock() to prevent shared access to
certain metric state. This lock is taken as part of doing collection, as well
as during metric.labels().

We hit a deadlock where our stack sampler signal arrived during a collection,
when the lock was held. This meant that flamegraph.labels() blocked forever,
and the lock was never released, hanging all metrics collection.

Our solution is a hack, which is to reach into the internals of our metric object
and replace its lock with a dummy one. This is reasonably safe, but only as long as
the prometheus_client internal structure doesn't change signfigiantly.
6 years ago
Mike Lang b9c2921242 common.stats: Add a stacksampler that records sampled stacks to prometheus
This can then be used to generate flamegraphs
6 years ago
Mike Lang 5175b099af common: Split segment-related stuff into its own module
We still import them into __init__.py so they're accessible externally just the same
6 years ago
Mike Lang 6f84a23ba6 common: Split stats-related stuff into its own module
We still import them into __init__.py so they're accessible externally just the same
6 years ago
Mike Lang 8fe2fec958 common: convert from module to package 6 years ago