ClaudeSession: RLock so switch_model/restart don't self-deadlock#495
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session.prompt acquires self._lock via ``with self:`` then calls switch_model, which ALSO does ``with self._lock:`` to serialize the swap. threading.Lock is non-reentrant — the second acquire from the same thread blocks forever. restart() has the same shape. Use threading.RLock so the inner acquire is allowed to succeed when called from the outer context. Other callers (external threads) still serialize correctly because the RLock counter only increments for the owning thread. Unblocks set_status for phase-2 (emoji) when it needs to switch from sonnet back to opus — previously every set_status after the first phase hung because of this self-deadlock.
rhencke
approved these changes
Apr 14, 2026
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session.promptacquiresself._lockviawith self:then callsswitch_model, which ALSO doeswith self._lock:to serialize the swap.threading.Lockis non-reentrant — the second acquire from the same thread blocks forever.restart()has the same shape.Use
threading.RLockso the inner acquire is allowed when called from the outer context. Other callers (external threads) still serialize correctly because the RLock counter only increments for the owning thread.Unblocks
set_statuson phase-2 (emoji) when it needs to switch back to opus — everyset_statusafter the first phase was wedging on this self-deadlock.