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@lmielick lmielick commented Sep 4, 2025

Contrary to pthread_join on Windows WaitForSingleObject does not destroy the thread handle. Add missing CloseHandle call to avoid a handle leak.

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llvmbot commented Sep 4, 2025

@llvm/pr-subscribers-platform-windows

Author: Lukasz Mielicki (lmielick)

Changes

Contrary to pthread_join on Windows WaitForSingleObject does not destroy the thread handle. Add missing CloseHandle call to avoid a handle leak.


Full diff: https://github.com/llvm/llvm-project/pull/156854.diff

1 Files Affected:

  • (modified) llvm/lib/Support/Windows/Threading.inc (+3)
diff --git a/llvm/lib/Support/Windows/Threading.inc b/llvm/lib/Support/Windows/Threading.inc
index b11f216adeba4..fd872a2b133e9 100644
--- a/llvm/lib/Support/Windows/Threading.inc
+++ b/llvm/lib/Support/Windows/Threading.inc
@@ -42,6 +42,9 @@ void llvm_thread_join_impl(HANDLE hThread) {
   if (::WaitForSingleObject(hThread, INFINITE) == WAIT_FAILED) {
     ReportLastErrorFatal("WaitForSingleObject failed");
   }
+  if (::CloseHandle(hThread) == FALSE) {
+    ReportLastErrorFatal("CloseHandle failed");
+  }
 }
 
 void llvm_thread_detach_impl(HANDLE hThread) {

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llvmbot commented Sep 4, 2025

@llvm/pr-subscribers-llvm-support

Author: Lukasz Mielicki (lmielick)

Changes

Contrary to pthread_join on Windows WaitForSingleObject does not destroy the thread handle. Add missing CloseHandle call to avoid a handle leak.


Full diff: https://github.com/llvm/llvm-project/pull/156854.diff

1 Files Affected:

  • (modified) llvm/lib/Support/Windows/Threading.inc (+3)
diff --git a/llvm/lib/Support/Windows/Threading.inc b/llvm/lib/Support/Windows/Threading.inc
index b11f216adeba4..fd872a2b133e9 100644
--- a/llvm/lib/Support/Windows/Threading.inc
+++ b/llvm/lib/Support/Windows/Threading.inc
@@ -42,6 +42,9 @@ void llvm_thread_join_impl(HANDLE hThread) {
   if (::WaitForSingleObject(hThread, INFINITE) == WAIT_FAILED) {
     ReportLastErrorFatal("WaitForSingleObject failed");
   }
+  if (::CloseHandle(hThread) == FALSE) {
+    ReportLastErrorFatal("CloseHandle failed");
+  }
 }
 
 void llvm_thread_detach_impl(HANDLE hThread) {

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lmielick commented Sep 4, 2025

@aganea @mstorsjo please have a look

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@dpaoliello dpaoliello left a comment

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LGTM - thread::join clears the handle after calling this, so we are definitely leaking at the moment:

void thread::join() {
llvm_thread_join_impl(Thread);
Thread = native_handle_type();
}

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LGTM, just a nit.

@aganea aganea enabled auto-merge (squash) September 8, 2025 11:10
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github-actions bot commented Sep 8, 2025

✅ With the latest revision this PR passed the C/C++ code formatter.

auto-merge was automatically disabled September 8, 2025 11:22

Head branch was pushed to by a user without write access

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tru commented Sep 8, 2025

@lmielick do you want me to merge it for you?

@tru tru closed this Sep 8, 2025
@tru tru reopened this Sep 8, 2025
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tru commented Sep 8, 2025

(sorry pressed the wrong button and accidentally closed it).

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lmielick commented Sep 8, 2025

@lmielick do you want me to merge it for you?

yes please. Thank you @tru!

@tru tru merged commit 6c0f7a5 into llvm:main Sep 8, 2025
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github-actions bot commented Sep 8, 2025

@lmielick Congratulations on having your first Pull Request (PR) merged into the LLVM Project!

Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR.

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If you don't get any reports, no action is required from you. Your changes are working as expected, well done!

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5 participants