Don't run pthread exit handlers on application exit (#14751)

It should only be executed when a thread is exiting (or when
pthread_exit is explicitly called).

This reverts commit 6d3e78c partially.

src/library_pthread.js

@@ -1034,8 +1034,10 @@ var LibraryPThread = {
 
   __pthread_exit_js__deps: ['exit'],
   __pthread_exit_js: function(status) {
-    if (!ENVIRONMENT_IS_PTHREAD) _exit(status);
-    else PThread.threadExit(status);
+    if (!ENVIRONMENT_IS_PTHREAD) {
+      PThread.runExitHandlers();
+      _exit(status);
+    } else PThread.threadExit(status);
     // pthread_exit is marked noReturn, so we must not return from it.
     throw 'unwind';
   },

src/postamble_minimal.js

@@ -24,9 +24,6 @@ function run() {
   var ret = _main();
 
 #if EXIT_RUNTIME
-#if USE_PTHREADS
-  PThread.runExitHandlers();
-#endif
   callRuntimeCallbacks(__ATEXIT__);
   <<< ATEXITS >>>
 #endif

src/preamble.js

@@ -419,9 +419,6 @@ function exitRuntime() {
   checkStackCookie();
 #endif
 #if USE_PTHREADS
-#if EXIT_RUNTIME
-  PThread.runExitHandlers();
-#endif
   if (ENVIRONMENT_IS_PTHREAD) return; // PThreads reuse the runtime from the main thread.
 #endif
 #if EXIT_RUNTIME

tests/pthread/test_pthread_setspecific_mainthread.c

@@ -4,12 +4,19 @@
 // found in the LICENSE file.
 
 #include <assert.h>
-#include <stdio.h>
 #include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 void destructor(void* arg) {
+#if defined(RETURN) || defined(EXIT)
+  // The destructors for thread-specific data should only be executed
+  // when a thread exits or when pthread_exit is explicitly called.
+  assert(0 && "pthread key dtor should not be executed on application exit");
+#else
   printf("destructor: %ld\n", (long)arg);
   assert(arg == (void*)42);
+#endif
 }
 
 int main() {
@@ -20,5 +27,12 @@ int main() {
   pthread_setspecific(key, (void*)42);
   val = pthread_getspecific(key);
   assert(val == (void*)42);
+  printf("done!\n");
+#ifdef RETURN
   return 0;
+#elif defined(EXIT)
+  exit(0);
+#else
+  pthread_exit(0);
+#endif
 }

tests/pthread/test_pthread_setspecific_mainthread.out

@@ -1 +1,2 @@
+done!
 destructor: 42

tests/test_core.py

@@ -2335,6 +2335,11 @@ The current type of b is: 9
   @node_pthreads
   def test_pthread_setspecific_mainthread(self):
     self.set_setting('EXIT_RUNTIME')
+    print('.. return')
+    self.do_runf(test_file('pthread/test_pthread_setspecific_mainthread.c'), 'done!', emcc_args=['-DRETURN'])
+    print('.. exit')
+    self.do_runf(test_file('pthread/test_pthread_setspecific_mainthread.c'), 'done!', emcc_args=['-DEXIT'])
+    print('.. pthread_exit')
     self.do_run_in_out_file_test('pthread/test_pthread_setspecific_mainthread.c')
 
   @node_pthreads