fix: race race in attaching to existing sessions#366
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ethanpailes merged 2 commits intomasterfrom May 7, 2026
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This patch migrates from stdlib mutexes to parking lot mutexes. This probably provides some small perf win, but the main reason I want it is for the arc_lock method that I'm going to need in order to fix a race condition in how we handle attaches.
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In practice this should only happen during a suspend or something like that. That's how I encountered the issue. |
This patch fixes a race condition that could happen when two different procs raced to attach to a given session. Since we release the session lock breifly as part of the attach handshake, we were leaving a window open in which two racing attaches could trample on one another. The regression test in this patch shows the issue in detail. To fix the issue, I had select_shell_desc start returning the lock guard for the session so that there was no gap in which the lock was released. In order to do that, I needed to switch to use parking_lot mutexes, since it is impossible to return the lock guard for an Arc<Mutex<T>> using the stdlib types.
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I split this up into one commit for the Mutex migration and one for the actual fix to make it easier to review in isolation. |
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maxhbooth
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May 7, 2026
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n/a I just noticed this when I logged on this morning
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This PR was:
I wrote the fix, gemini wrote the test and helped with diagnosis.
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