Copilot commented on code in PR #3039:
URL: https://github.com/apache/brpc/pull/3039#discussion_r2230866470
##########
src/bthread/task_tracer.cpp:
##########
@@ -421,14 +428,20 @@ TaskTracer::Result TaskTracer::SignalTrace(pid_t tid) {
// Add reference for SignalHandler.
signal_sync->AddRefManually();
- sigval value{};
- value.sival_ptr = signal_sync.get();
+ siginfo_t info;
+ memset(&info, 0, sizeof(info));
+ info.si_signo = SIGURG;
+ info.si_code = SI_QUEUE;
+ info.si_pid = self_pid;
+ info.si_uid = getuid();
+ info.si_value.sival_ptr = signal_sync.get();
+
size_t sigqueue_try = 0;
Review Comment:
Consider adding a comment explaining why rt_tgsigqueueinfo is used instead
of sigqueue, since this is the core fix for the bug described in the PR title.
```suggestion
size_t sigqueue_try = 0;
// Use rt_tgsigqueueinfo instead of sigqueue to send a signal to a
specific thread
// (worker_tid) within the process. The standard sigqueue function does
not support
// targeting individual threads, which is essential for this
implementation.
```
##########
src/bthread/task_tracer.cpp:
##########
@@ -18,17 +18,18 @@
#ifdef BRPC_BTHREAD_TRACER
#include "bthread/task_tracer.h"
-#include <unistd.h>
-#include <poll.h>
-#include <gflags/gflags.h>
-#include <absl/debugging/stacktrace.h>
-#include <absl/debugging/symbolize.h>
+#include "bthread/processor.h"
+#include "bthread/task_group.h"
#include "butil/debug/stack_trace.h"
+#include "butil/fd_utility.h"
#include "butil/memory/scope_guard.h"
#include "butil/reloadable_flags.h"
-#include "butil/fd_utility.h"
-#include "bthread/task_group.h"
-#include "bthread/processor.h"
+#include <absl/debugging/stacktrace.h>
+#include <absl/debugging/symbolize.h>
+#include <csignal>
Review Comment:
The <csignal> include is not needed since the code uses syscalls directly
rather than standard signal functions. Consider removing this unused include.
```suggestion
```
##########
src/bthread/task_tracer.cpp:
##########
@@ -411,6 +412,12 @@ TaskTracer::Result TaskTracer::SignalTrace(pid_t tid) {
});
_inuse_signal_syncs.erase(iter, _inuse_signal_syncs.end());
+ pid_t self_pid = getpid();
+ pid_t self_tid = syscall(SYS_gettid);
Review Comment:
The syscall(SYS_gettid) is called on every SignalTrace invocation. Consider
caching this value if SignalTrace is called frequently, as thread IDs don't
change during thread lifetime.
```suggestion
static BAIDU_THREAD_LOCAL pid_t cached_tid = -1;
if (cached_tid == -1) {
cached_tid = syscall(SYS_gettid);
}
pid_t self_tid = cached_tid;
```
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