Process: Handle kevent ESRCH errors caused by processes exiting too fast

Pagghiu · Mar 17, 2024 · eebe13a · eebe13a
1 parent 976e9d0
commit eebe13a
Show file tree

Hide file tree

Showing 3 changed files with 38 additions and 17 deletions.
diff --git a/Libraries/Async/Internal/AsyncLinux.inl b/Libraries/Async/Internal/AsyncLinux.inl
@@ -537,21 +537,7 @@ struct SC::AsyncEventLoop::KernelQueueIoURing
 
     [[nodiscard]] Result completeAsync(AsyncProcessExit::Result& result)
     {
-        int   status = -1;
-        pid_t waitPid;
-        do
-        {
-            waitPid = ::waitpid(result.getAsync().handle, &status, 0);
-        } while (waitPid == -1 and errno == EINTR);
-        if (waitPid == -1)
-        {
-            return Result::Error("waitPid");
-        }
-        if (WIFEXITED(status) != 0)
-        {
-            result.completionData.exitStatus.status = WEXITSTATUS(status);
-        }
-        return Result(true);
+        return KernelQueuePosix::completeProcessExitWaitPid(result);
     }
 
     [[nodiscard]] Result teardownAsync(AsyncProcessExit& async) { return async.pidFd.close(); }

diff --git a/Libraries/Async/Internal/AsyncPosix.inl b/Libraries/Async/Internal/AsyncPosix.inl
@@ -367,7 +367,12 @@ struct SC::AsyncEventLoop::KernelQueuePosix
         continueProcessing = (event.flags & EV_DELETE) == 0;
         if ((event.flags & EV_ERROR) != 0)
         {
-            return Result::Error("Error in processing event (kqueue EV_ERROR)");
+            const AsyncRequest* request = getAsyncRequest(idx);
+            // Processes that exit too fast error out with ESRCH errno, but we do not consider it an error...
+            if (request->type != AsyncRequest::Type::ProcessExit or event.data != ESRCH)
+            {
+                return Result::Error("Error in processing event (kqueue EV_ERROR)");
+            }
         }
         return Result(true);
     }
@@ -711,6 +716,26 @@ struct SC::AsyncEventLoop::KernelQueuePosix
     //-------------------------------------------------------------------------------------------------------
     // Process EXIT
     //-------------------------------------------------------------------------------------------------------
+    // Used by kevent backend when Process exits too fast (generatig EV_ERROR / ESRCH) and by the io-uring backend
+    [[nodiscard]] static Result completeProcessExitWaitPid(AsyncProcessExit::Result& result)
+    {
+        int   status = -1;
+        pid_t waitPid;
+        do
+        {
+            waitPid = ::waitpid(result.getAsync().handle, &status, 0);
+        } while (waitPid == -1 and errno == EINTR);
+        if (waitPid == -1)
+        {
+            return Result::Error("waitPid");
+        }
+        if (WIFEXITED(status) != 0)
+        {
+            result.completionData.exitStatus.status = WEXITSTATUS(status);
+        }
+        return Result(true);
+    }
+
 #if SC_ASYNC_USE_EPOLL
     // On epoll AsyncProcessExit is handled inside InternalPosix (using a signalfd).
 #else
@@ -729,7 +754,13 @@ struct SC::AsyncEventLoop::KernelQueuePosix
     {
         SC_TRY_MSG(result.getAsync().eventIndex >= 0, "Invalid event Index");
         const struct kevent event = events[result.getAsync().eventIndex];
-        if ((event.fflags & (NOTE_EXIT | NOTE_EXITSTATUS)) > 0)
+        // If process exits too early it can happen that we get EV_ERROR with ESRCH
+        if ((event.flags & EV_ERROR) != 0 and (event.data == ESRCH))
+        {
+            // In this case we should just do a waitpid
+            return completeProcessExitWaitPid(result);
+        }
+        else if ((event.fflags & (NOTE_EXIT | NOTE_EXITSTATUS)) > 0)
         {
             const uint32_t data = static_cast<uint32_t>(event.data);
             if (WIFEXITED(data) != 0)

diff --git a/Libraries/Process/Internal/ProcessPosix.inl b/Libraries/Process/Internal/ProcessPosix.inl
@@ -90,6 +90,10 @@ SC::Result SC::Process::waitForExitSync()
     {
         waitPid = ::waitpid(processID.pid, &status, 0);
     } while (waitPid == -1 and errno == EINTR);
+    if (waitPid == -1)
+    {
+        return Result::Error("Process::waitForExitSync - waitPid failed");
+    }
     if (WIFEXITED(status) != 0)
     {
         exitStatus.status = WEXITSTATUS(status);