Disable profiler with feature - #58942
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cole-miller
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Jun 9, 2026
- #58813 - #58942 Self-Review Checklist: - [x] I've reviewed my own diff for quality, security, and reliability - [x] Unsafe blocks (if any) have justifying comments - [x] The content adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable Release Notes: - N/A --------- Co-authored-by: Yara 🏳️⚧️ <git@yara.blue>
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jonx
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Jul 17, 2026
Reopening @yara-blue's change to try to fix CI: > This disables the GPUI profiler by default, it is opt in using the feature gpui/profiler. We had one report of a possible deadlock, until that is resolved the profiler will be disabled. By doing this with a feature we can keep the code and fix forward on nightly post release. It will also be useful to other GPUI users who are not using the profiler infrastructure and now no longer need to pay the overhead (0.1%). Self-Review Checklist: - [x] I've reviewed my own diff for quality, security, and reliability - [x] Unsafe blocks (if any) have justifying comments - [x] The content adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable Release Notes: - N/A --------- Co-authored-by: Yara <git@yara.blue>
ddeityy
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Jul 24, 2026
…tries#61584) ### Summary PR zed-industries#58942 disabled the performance profiler within Zed because there was a race condition that caused Zed to hang forever due to a deadlock involving the foreground thread. This PR fixes the deadlock and re-enables the performance profiler. The deadlock happened because `ThreadTimings::drop()` locks `GLOBAL_THREAD_TIMINGS`, and that drop could run in places where `GLOBAL_THREAD_TIMINGS` was already locked: the collection paths (`get_all_timings`, `take_all_stats`, `set_trace_enabled(false)`) held the global lock while upgrading and then dropping per-thread `Arc<GuardedTaskTimings>` handles. If a worker thread exited in that window (e.g. GCD reclaiming an idle thread), the collector inherited the last strong reference, and dropping it ran `ThreadTimings::drop` -> `GLOBAL_THREAD_TIMINGS.lock()` reentrantly on the same thread. The spinlock is not reentrant, so the thread spun forever while holding the lock, hanging every other thread that touched the profiler. The fix: hold `GLOBAL_THREAD_TIMINGS` only long enough to upgrade the `Weak` handles (`upgraded_thread_timings()`), and release it before any per-thread buffer is locked, copied, or dropped. A last-reference drop now always runs with the global lock free. As a side benefit, the up-to-16MiB per-thread buffer copies no longer happen under the global lock. ### Diagram ```mermaid sequenceDiagram participant C as Collector thread (get_all_timings) participant G as GLOBAL_THREAD_TIMINGS (spin::Mutex) participant T as Worker thread (exiting) Note over T: holds the only strong Arc<br/>in its THREAD_TIMINGS TLS C->>G: lock() — guard held for entire collection C->>C: Weak::upgrade() (strong: 1 → 2) T->>T: thread exits, TLS destructor drops its Arc (strong: 2 → 1) C->>C: temp Arc dropped at end of iteration (strong: 1 → 0) C->>C: ThreadTimings::drop() runs on collector thread C->>G: lock() again — already held by this thread Note over C,G: spin lock is not reentrant → spins forever,<br/>every other profiler user spins behind it Note over C,T: Fix: upgrade all Weaks under the lock, release it,<br/>then lock/copy/drop per-thread handles — the reentrant<br/>drop can now only ever run with the global lock free ``` Release Notes: - Fixed a deadlock in the performance profiler and re-enabled it (`zed: open performance profiler`)
0arm
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Jul 26, 2026
…tries#61584) ### Summary PR zed-industries#58942 disabled the performance profiler within Zed because there was a race condition that caused Zed to hang forever due to a deadlock involving the foreground thread. This PR fixes the deadlock and re-enables the performance profiler. The deadlock happened because `ThreadTimings::drop()` locks `GLOBAL_THREAD_TIMINGS`, and that drop could run in places where `GLOBAL_THREAD_TIMINGS` was already locked: the collection paths (`get_all_timings`, `take_all_stats`, `set_trace_enabled(false)`) held the global lock while upgrading and then dropping per-thread `Arc<GuardedTaskTimings>` handles. If a worker thread exited in that window (e.g. GCD reclaiming an idle thread), the collector inherited the last strong reference, and dropping it ran `ThreadTimings::drop` -> `GLOBAL_THREAD_TIMINGS.lock()` reentrantly on the same thread. The spinlock is not reentrant, so the thread spun forever while holding the lock, hanging every other thread that touched the profiler. The fix: hold `GLOBAL_THREAD_TIMINGS` only long enough to upgrade the `Weak` handles (`upgraded_thread_timings()`), and release it before any per-thread buffer is locked, copied, or dropped. A last-reference drop now always runs with the global lock free. As a side benefit, the up-to-16MiB per-thread buffer copies no longer happen under the global lock. ### Diagram ```mermaid sequenceDiagram participant C as Collector thread (get_all_timings) participant G as GLOBAL_THREAD_TIMINGS (spin::Mutex) participant T as Worker thread (exiting) Note over T: holds the only strong Arc<br/>in its THREAD_TIMINGS TLS C->>G: lock() — guard held for entire collection C->>C: Weak::upgrade() (strong: 1 → 2) T->>T: thread exits, TLS destructor drops its Arc (strong: 2 → 1) C->>C: temp Arc dropped at end of iteration (strong: 1 → 0) C->>C: ThreadTimings::drop() runs on collector thread C->>G: lock() again — already held by this thread Note over C,G: spin lock is not reentrant → spins forever,<br/>every other profiler user spins behind it Note over C,T: Fix: upgrade all Weaks under the lock, release it,<br/>then lock/copy/drop per-thread handles — the reentrant<br/>drop can now only ever run with the global lock free ``` Release Notes: - Fixed a deadlock in the performance profiler and re-enabled it (`zed: open performance profiler`)
jolutz
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Aug 8, 2026
- zed-industries#58813 - zed-industries#58942 Self-Review Checklist: - [x] I've reviewed my own diff for quality, security, and reliability - [x] Unsafe blocks (if any) have justifying comments - [x] The content adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable Release Notes: - N/A --------- Co-authored-by: Yara 🏳️⚧️ <git@yara.blue>
jolutz
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Aug 8, 2026
Reopening @yara-blue's change to try to fix CI: > This disables the GPUI profiler by default, it is opt in using the feature gpui/profiler. We had one report of a possible deadlock, until that is resolved the profiler will be disabled. By doing this with a feature we can keep the code and fix forward on nightly post release. It will also be useful to other GPUI users who are not using the profiler infrastructure and now no longer need to pay the overhead (0.1%). Self-Review Checklist: - [x] I've reviewed my own diff for quality, security, and reliability - [x] Unsafe blocks (if any) have justifying comments - [x] The content adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable Release Notes: - N/A --------- Co-authored-by: Yara <git@yara.blue>
jolutz
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to jolutz/zed
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Aug 8, 2026
…tries#61584) ### Summary PR zed-industries#58942 disabled the performance profiler within Zed because there was a race condition that caused Zed to hang forever due to a deadlock involving the foreground thread. This PR fixes the deadlock and re-enables the performance profiler. The deadlock happened because `ThreadTimings::drop()` locks `GLOBAL_THREAD_TIMINGS`, and that drop could run in places where `GLOBAL_THREAD_TIMINGS` was already locked: the collection paths (`get_all_timings`, `take_all_stats`, `set_trace_enabled(false)`) held the global lock while upgrading and then dropping per-thread `Arc<GuardedTaskTimings>` handles. If a worker thread exited in that window (e.g. GCD reclaiming an idle thread), the collector inherited the last strong reference, and dropping it ran `ThreadTimings::drop` -> `GLOBAL_THREAD_TIMINGS.lock()` reentrantly on the same thread. The spinlock is not reentrant, so the thread spun forever while holding the lock, hanging every other thread that touched the profiler. The fix: hold `GLOBAL_THREAD_TIMINGS` only long enough to upgrade the `Weak` handles (`upgraded_thread_timings()`), and release it before any per-thread buffer is locked, copied, or dropped. A last-reference drop now always runs with the global lock free. As a side benefit, the up-to-16MiB per-thread buffer copies no longer happen under the global lock. ### Diagram ```mermaid sequenceDiagram participant C as Collector thread (get_all_timings) participant G as GLOBAL_THREAD_TIMINGS (spin::Mutex) participant T as Worker thread (exiting) Note over T: holds the only strong Arc<br/>in its THREAD_TIMINGS TLS C->>G: lock() — guard held for entire collection C->>C: Weak::upgrade() (strong: 1 → 2) T->>T: thread exits, TLS destructor drops its Arc (strong: 2 → 1) C->>C: temp Arc dropped at end of iteration (strong: 1 → 0) C->>C: ThreadTimings::drop() runs on collector thread C->>G: lock() again — already held by this thread Note over C,G: spin lock is not reentrant → spins forever,<br/>every other profiler user spins behind it Note over C,T: Fix: upgrade all Weaks under the lock, release it,<br/>then lock/copy/drop per-thread handles — the reentrant<br/>drop can now only ever run with the global lock free ``` Release Notes: - Fixed a deadlock in the performance profiler and re-enabled it (`zed: open performance profiler`)
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Reopening @yara-blue's change to try to fix CI:
Self-Review Checklist:
Release Notes: