I pointed Opus 4.7 (high effort) at proxy.ProcessGroup to identify any
race conditions in the swapping code. It found a race condition where
there is a small window in the fast path for routing a request to a
loaded model. There is a very small window where:
- model M1 is loaded and ready for requests
- a request, R1, for M1 comes in
- a request, R2, for M2 comes in almost immediately after
- R1 acquires the lock, sees M1 is loaded (fast path), releases the lock
`[race window]` and the request is ready to be forwarded
- the race window occurs between the release of the lock and the request
being forwarded
- the lock is released so requests can be handled concurrently
- R2 comes in within the `[race window]`, acquires the lock, triggers a
model swap to M2. stopping M1
- R1 is forwarded to a model that is unloaded or in the process of
shutting down creating an error response
In deployed systems the race window is very small and doesn't happen
often. However with #635 and PR #656 I though this deserved a bit more
attention. It is not concluded that this race is the cause of #635 but
the race is likely to happen more often under sustained or high load.
AI Note: Opus 4.7 x-high effort took about an hour to write the original
patch. With the pattern discovered the fix to matrix.go was very quick.
GLM 5.1 using the previous established patterns was able to easily write
the fix for ProcessGroup.StopProcesses().
Supersedes: #656
Updates: #277, #635
* proxy/config: create config package and migrate configuration
The configuration is become more complex as llama-swap adds more
advanced features. This commit moves config to its own package so it can
be developed independently of the proxy package.
Additionally, enforcing a public API for a configuration will allow
downstream usage to be more decoupled.
Sometimes upstreams can accept HTTP but never respond causing requests
to build up waiting for a response. This can block Process.Stop() as
that waits for inflight requests to finish. This change refactors the
code to not wait when attempting to shutdown the process.
Groups allows more control over swapping behaviour when a model is requested. The new groups feature provides three ways to control swapping: within the group, swapping out other groups or keep the models in the group loaded persistently (never swapped out).
Closes#96, #99 and #106.
Benson Wong