bio: fix doFastMemoryTest.

If one thread got SIGSEGV, function sigsegvHandler() would be triggered,
it would call bioKillThreads(). But call pthread_cancel() to cancel itself
would make it block. Also note that if SIGSEGV is caught by bio thread, it
should kill the main thread in order to give a positive report.

src/bio.c

@@ -268,10 +268,11 @@ void bioKillThreads(void) {
     int err, j;
 
     for (j = 0; j < BIO_NUM_OPS; j++) {
+        if (bio_threads[j] == pthread_self()) continue;
         if (bio_threads[j] && pthread_cancel(bio_threads[j]) == 0) {
             if ((err = pthread_join(bio_threads[j],NULL)) != 0) {
                 serverLog(LL_WARNING,
-                    "Bio thread for job type #%d can be joined: %s",
+                    "Bio thread for job type #%d can not be joined: %s",
                         j, strerror(err));
             } else {
                 serverLog(LL_WARNING,

src/debug.c

@@ -1565,12 +1565,32 @@ int memtest_test_linux_anonymous_maps(void) {
 }
 #endif
 
+static void killMainThread(void) {
+    int err;
+    if (pthread_self() != server.main_thread_id && pthread_cancel(server.main_thread_id) == 0) {
+        if ((err = pthread_join(server.main_thread_id,NULL)) != 0) {
+            serverLog(LL_WARNING, "main thread can not be joined: %s", strerror(err));
+        } else {
+            serverLog(LL_WARNING, "main thread terminated");
+        }
+    }
+}
+
+/* Kill the running threads (other than current) in an unclean way. This function
+ * should be used only when it's critical to stop the threads for some reason.
+ * Currently Redis does this only on crash (for instance on SIGSEGV) in order
+ * to perform a fast memory check without other threads messing with memory. */
+static void killThreads(void) {
+    killMainThread();
+    bioKillThreads();
+}
+
 void doFastMemoryTest(void) {
 #if defined(HAVE_PROC_MAPS)
     if (server.memcheck_enabled) {
         /* Test memory */
         serverLogRaw(LL_WARNING|LL_RAW, "\n------ FAST MEMORY TEST ------\n");
-        bioKillThreads();
+        killThreads();
         if (memtest_test_linux_anonymous_maps()) {
             serverLogRaw(LL_WARNING|LL_RAW,
                 "!!! MEMORY ERROR DETECTED! Check your memory ASAP !!!\n");

src/server.c

@@ -2879,6 +2879,7 @@ void initServer(void) {
     server.aof_state = server.aof_enabled ? AOF_ON : AOF_OFF;
     server.hz = server.config_hz;
     server.pid = getpid();
+    server.main_thread_id = pthread_self();
     server.current_client = NULL;
     server.fixed_time_expire = 0;
     server.clients = listCreate();
@@ -5174,7 +5175,6 @@ int iAmMaster(void) {
             (server.cluster_enabled && nodeIsMaster(server.cluster->myself)));
 }
 
-
 int main(int argc, char **argv) {
     struct timeval tv;
     int j;

src/server.h

@@ -1050,6 +1050,7 @@ struct clusterState;
 struct redisServer {
     /* General */
     pid_t pid;                  /* Main process pid. */
+    pthread_t main_thread_id;         /* Main thread id */
     char *configfile;           /* Absolute config file path, or NULL */
     char *executable;           /* Absolute executable file path. */
     char **exec_argv;           /* Executable argv vector (copy). */