Merge branch 'free_clients_during_loading' into unstable

src/ae.c

@@ -370,6 +370,7 @@ static int processTimeEvents(aeEventLoop *eventLoop) {
  * if flags has AE_DONT_WAIT set the function returns ASAP until all
  * the events that's possible to process without to wait are processed.
  * if flags has AE_CALL_AFTER_SLEEP set, the aftersleep callback is called.
+ * if flags has AE_CALL_BEFORE_SLEEP set, the beforesleep callback is called.
  *
  * The function returns the number of events processed. */
 int aeProcessEvents(aeEventLoop *eventLoop, int flags)
@@ -428,6 +429,9 @@ int aeProcessEvents(aeEventLoop *eventLoop, int flags)
             tvp = &tv;
         }
 
+        if (eventLoop->beforesleep != NULL && flags & AE_CALL_BEFORE_SLEEP)
+            eventLoop->beforesleep(eventLoop);
+
         /* Call the multiplexing API, will return only on timeout or when
          * some event fires. */
         numevents = aeApiPoll(eventLoop, tvp);
@@ -522,9 +526,9 @@ int aeWait(int fd, int mask, long long milliseconds) {
 void aeMain(aeEventLoop *eventLoop) {
     eventLoop->stop = 0;
     while (!eventLoop->stop) {
-        if (eventLoop->beforesleep != NULL)
-            eventLoop->beforesleep(eventLoop);
-        aeProcessEvents(eventLoop, AE_ALL_EVENTS|AE_CALL_AFTER_SLEEP);
+        aeProcessEvents(eventLoop, AE_ALL_EVENTS|
+                                   AE_CALL_BEFORE_SLEEP|
+                                   AE_CALL_AFTER_SLEEP);
     }
 }
 

src/ae.h

@@ -47,11 +47,12 @@
                            things to disk before sending replies, and want
                            to do that in a group fashion. */
 
-#define AE_FILE_EVENTS 1
-#define AE_TIME_EVENTS 2
+#define AE_FILE_EVENTS (1<<0)
+#define AE_TIME_EVENTS (1<<1)
 #define AE_ALL_EVENTS (AE_FILE_EVENTS|AE_TIME_EVENTS)
-#define AE_DONT_WAIT 4
-#define AE_CALL_AFTER_SLEEP 8
+#define AE_DONT_WAIT (1<<2)
+#define AE_CALL_BEFORE_SLEEP (1<<3)
+#define AE_CALL_AFTER_SLEEP (1<<4)
 
 #define AE_NOMORE -1
 #define AE_DELETED_EVENT_ID -1

src/connection.h

@@ -222,6 +222,6 @@ const char *connGetInfo(connection *conn, char *buf, size_t buf_len);
 
 /* Helpers for tls special considerations */
 int tlsHasPendingData();
-void tlsProcessPendingData();
+int tlsProcessPendingData();
 
 #endif  /* __REDIS_CONNECTION_H */

src/networking.c

@@ -1257,7 +1257,10 @@ void freeClientAsync(client *c) {
     pthread_mutex_unlock(&async_free_queue_mutex);
 }
 
-void freeClientsInAsyncFreeQueue(void) {
+/* Free the clietns marked as CLOSE_ASAP, return the number of clients
+ * freed. */
+int freeClientsInAsyncFreeQueue(void) {
+    int freed = listLength(server.clients_to_close);
     while (listLength(server.clients_to_close)) {
         listNode *ln = listFirst(server.clients_to_close);
         client *c = listNodeValue(ln);
@@ -1266,6 +1269,7 @@ void freeClientsInAsyncFreeQueue(void) {
         freeClient(c);
         listDelNode(server.clients_to_close,ln);
     }
+    return freed;
 }
 
 /* Return a client by ID, or NULL if the client ID is not in the set
@@ -2852,9 +2856,8 @@ int clientsArePaused(void) {
  * write, close sequence needed to serve a client.
  *
  * The function returns the total number of events processed. */
-int processEventsWhileBlocked(void) {
+void processEventsWhileBlocked(void) {
     int iterations = 4; /* See the function top-comment. */
-    int count = 0;
 
     /* Note: when we are processing events while blocked (for instance during
      * busy Lua scripts), we set a global flag. When such flag is set, we
@@ -2862,14 +2865,17 @@ int processEventsWhileBlocked(void) {
      * See https://github.com/antirez/redis/issues/6988 for more info. */
     ProcessingEventsWhileBlocked = 1;
     while (iterations--) {
-        int events = 0;
-        events += aeProcessEvents(server.el, AE_FILE_EVENTS|AE_DONT_WAIT);
-        events += handleClientsWithPendingWrites();
+        long long startval = server.events_processed_while_blocked;
+        long long ae_events = aeProcessEvents(server.el,
+            AE_FILE_EVENTS|AE_DONT_WAIT|
+            AE_CALL_BEFORE_SLEEP|AE_CALL_AFTER_SLEEP);
+        /* Note that server.events_processed_while_blocked will also get
+         * incremeted by callbacks called by the event loop handlers. */
+        server.events_processed_while_blocked += ae_events;
+        long long events = server.events_processed_while_blocked - startval;
         if (!events) break;
-        count += events;
     }
     ProcessingEventsWhileBlocked = 0;
-    return count;
 }
 
 /* ==========================================================================

src/server.c

@@ -2087,12 +2087,40 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
     return 1000/server.hz;
 }
 
+extern int ProcessingEventsWhileBlocked;
+
 /* This function gets called every time Redis is entering the
  * main loop of the event driven library, that is, before to sleep
- * for ready file descriptors. */
+ * for ready file descriptors.
+ *
+ * Note: This function is (currently) called from two functions:
+ * 1. aeMain - The main server loop
+ * 2. processEventsWhileBlocked - Process clients during RDB/AOF load
+ *
+ * If it was called from processEventsWhileBlocked we don't want
+ * to perform all actions (For example, we don't want to expire
+ * keys), but we do need to perform some actions.
+ *
+ * The most important is freeClientsInAsyncFreeQueue but we also
+ * call some other low-risk functions. */
 void beforeSleep(struct aeEventLoop *eventLoop) {
     UNUSED(eventLoop);
 
+    /* Just call a subset of vital functions in case we are re-entering
+     * the event loop from processEventsWhileBlocked(). Note that in this
+     * case we keep track of the number of events we are processing, since
+     * processEventsWhileBlocked() wants to stop ASAP if there are no longer
+     * events to handle. */
+    if (ProcessingEventsWhileBlocked) {
+        uint64_t processed = 0;
+        processed += handleClientsWithPendingReadsUsingThreads();
+        processed += tlsProcessPendingData();
+        processed += handleClientsWithPendingWrites();
+        processed += freeClientsInAsyncFreeQueue();
+        server.events_processed_while_blocked += processed;
+        return;
+    }
+
     /* Handle precise timeouts of blocked clients. */
     handleBlockedClientsTimeout();
 
@@ -2171,7 +2199,10 @@ void beforeSleep(struct aeEventLoop *eventLoop) {
  * the different events callbacks. */
 void afterSleep(struct aeEventLoop *eventLoop) {
     UNUSED(eventLoop);
-    if (moduleCount()) moduleAcquireGIL();
+
+    if (!ProcessingEventsWhileBlocked) {
+        if (moduleCount()) moduleAcquireGIL();
+    }
 }
 
 /* =========================== Server initialization ======================== */
@@ -2737,6 +2768,7 @@ void initServer(void) {
     server.clients_waiting_acks = listCreate();
     server.get_ack_from_slaves = 0;
     server.clients_paused = 0;
+    server.events_processed_while_blocked = 0;
     server.system_memory_size = zmalloc_get_memory_size();
 
     if (server.tls_port && tlsConfigure(&server.tls_ctx_config) == C_ERR) {
@@ -2879,6 +2911,11 @@ void initServer(void) {
                 "blocked clients subsystem.");
     }
 
+    /* Register before and after sleep handlers (note this needs to be done
+     * before loading persistence since it is used by processEventsWhileBlocked. */
+    aeSetBeforeSleepProc(server.el,beforeSleep);
+    aeSetAfterSleepProc(server.el,afterSleep);
+
     /* Open the AOF file if needed. */
     if (server.aof_state == AOF_ON) {
         server.aof_fd = open(server.aof_filename,
@@ -5135,8 +5172,6 @@ int main(int argc, char **argv) {
     }
 
     redisSetCpuAffinity(server.server_cpulist);
-    aeSetBeforeSleepProc(server.el,beforeSleep);
-    aeSetAfterSleepProc(server.el,afterSleep);
     aeMain(server.el);
     aeDeleteEventLoop(server.el);
     return 0;

src/server.h

@@ -1095,6 +1095,7 @@ struct redisServer {
                                    queries. Will still serve RESP2 queries. */
     int io_threads_num;         /* Number of IO threads to use. */
     int io_threads_do_reads;    /* Read and parse from IO threads? */
+    long long events_processed_while_blocked; /* processEventsWhileBlocked() */
 
     /* RDB / AOF loading information */
     int loading;                /* We are loading data from disk if true */
@@ -1652,7 +1653,7 @@ void rewriteClientCommandVector(client *c, int argc, ...);
 void rewriteClientCommandArgument(client *c, int i, robj *newval);
 void replaceClientCommandVector(client *c, int argc, robj **argv);
 unsigned long getClientOutputBufferMemoryUsage(client *c);
-void freeClientsInAsyncFreeQueue(void);
+int freeClientsInAsyncFreeQueue(void);
 void asyncCloseClientOnOutputBufferLimitReached(client *c);
 int getClientType(client *c);
 int getClientTypeByName(char *name);
@@ -1662,7 +1663,7 @@ void disconnectSlaves(void);
 int listenToPort(int port, int *fds, int *count);
 void pauseClients(mstime_t duration);
 int clientsArePaused(void);
-int processEventsWhileBlocked(void);
+void processEventsWhileBlocked(void);
 int handleClientsWithPendingWrites(void);
 int handleClientsWithPendingWritesUsingThreads(void);
 int handleClientsWithPendingReadsUsingThreads(void);

src/tls.c

@@ -768,15 +768,17 @@ int tlsHasPendingData() {
     return listLength(pending_list) > 0;
 }
 
-void tlsProcessPendingData() {
+int tlsProcessPendingData() {
     listIter li;
     listNode *ln;
 
+    int processed = listLength(pending_list);
     listRewind(pending_list,&li);
     while((ln = listNext(&li))) {
         tls_connection *conn = listNodeValue(ln);
         tlsHandleEvent(conn, AE_READABLE);
     }
+    return processed;
 }
 
 #else   /* USE_OPENSSL */
@@ -804,7 +806,8 @@ int tlsHasPendingData() {
     return 0;
 }
 
-void tlsProcessPendingData() {
+int tlsProcessPendingData() {
+    return 0;
 }
 
 #endif

tests/integration/rdb.tcl

@@ -128,4 +128,56 @@ start_server {} {
         # make sure the server is still writable
         r set x xx
     }
+}
+
+test {client freed during loading} {
+    start_server [list overrides [list key-load-delay 10 rdbcompression no]] {
+        # create a big rdb that will take long to load. it is important
+        # for keys to be big since the server processes events only once in 2mb.
+        # 100mb of rdb, 100k keys will load in more than 1 second
+        r debug populate 100000 key 1000
+
+        catch {
+            r debug restart
+        }
+
+        set stdout [srv 0 stdout]
+        while 1 {
+            # check that the new server actually started and is ready for connections
+            if {[exec grep -i "Server initialized" | wc -l < $stdout] > 1} {
+                break
+            }
+            after 10
+        }
+        # make sure it's still loading
+        assert_equal [s loading] 1
+
+        # connect and disconnect 10 clients
+        set clients {}
+        for {set j 0} {$j < 10} {incr j} {
+            lappend clients [redis_deferring_client]
+        }
+        foreach rd $clients {
+            $rd debug log bla
+        }
+        foreach rd $clients {
+            $rd read
+        }
+        foreach rd $clients {
+            $rd close
+        }
+
+        # make sure the server freed the clients
+        wait_for_condition 100 100 {
+            [s connected_clients] < 3
+        } else {
+            fail "clients didn't disconnect"
+        }
+
+        # make sure it's still loading
+        assert_equal [s loading] 1
+
+        # no need to keep waiting for loading to complete
+        exec kill [srv 0 pid]
+    }
 }