(zookeeper) branch branch-3.9 updated: ZOOKEEPER-4858: Remove the lock contention between snapshotting and the sync operation

[kezhuw]

This is an automated email from the ASF dual-hosted git repository.

kezhuw pushed a commit to branch branch-3.9
in repository https://gitbox.apache.org/repos/asf/zookeeper.git


The following commit(s) were added to refs/heads/branch-3.9 by this push:
     new d2e6c2145 ZOOKEEPER-4858: Remove the lock contention between 
snapshotting and the sync operation
d2e6c2145 is described below

commit d2e6c21450946af2f89a101a356049fb9a520c22
Author: li4wang <68786536+li4w...@users.noreply.github.com>
AuthorDate: Fri Dec 20 20:14:33 2024 -0800

    ZOOKEEPER-4858: Remove the lock contention between snapshotting and the 
sync operation
    
    Reviewers: anmolnar, kezhuw
    Author: li4wang
    Closes #2185 from li4wang/ZOOKEEPER-4858
    
    (cherry picked from commit c0e92411fbb38025d4cd257835cf5e4afeea4956)
    Signed-off-by: Kezhu Wang <kez...@apache.org>
---
 .../org/apache/zookeeper/server/ZooKeeperServer.java    | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git 
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
 
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
index 8e291f869..fc677b329 100644
--- 
a/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
+++ 
b/zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
@@ -135,6 +135,8 @@ public class ZooKeeperServer implements SessionExpirer, 
ServerStats.Provider {
     public static final String CLOSE_SESSION_TXN_ENABLED = 
"zookeeper.closeSessionTxn.enabled";
     private static boolean closeSessionTxnEnabled = true;
     private volatile CountDownLatch restoreLatch;
+    // exclusive lock for taking snapshot and restore
+    private final Object snapshotAndRestoreLock = new Object();
 
     static {
         LOG = LoggerFactory.getLogger(ZooKeeperServer.class);
@@ -565,11 +567,13 @@ public class ZooKeeperServer implements SessionExpirer, 
ServerStats.Provider {
      * @return file snapshot file object
      * @throws IOException
      */
-    public synchronized File takeSnapshot(boolean syncSnap, boolean isSevere) 
throws IOException {
+    public File takeSnapshot(boolean syncSnap, boolean isSevere) throws 
IOException {
         long start = Time.currentElapsedTime();
         File snapFile = null;
         try {
-            snapFile = txnLogFactory.save(zkDb.getDataTree(), 
zkDb.getSessionWithTimeOuts(), syncSnap);
+            synchronized (snapshotAndRestoreLock) {
+                snapFile = txnLogFactory.save(zkDb.getDataTree(), 
zkDb.getSessionWithTimeOuts(), syncSnap);
+            }
         } catch (IOException e) {
             if (isSevere) {
                 LOG.error("Severe unrecoverable error, exiting", e);
@@ -593,7 +597,7 @@ public class ZooKeeperServer implements SessionExpirer, 
ServerStats.Provider {
      * @Return last processed zxid
      * @throws IOException
      */
-    public synchronized long restoreFromSnapshot(final InputStream 
inputStream) throws IOException {
+    public long restoreFromSnapshot(final InputStream inputStream) throws 
IOException {
         if (inputStream == null) {
             throw new IllegalArgumentException("InputStream can not be null 
when restoring from snapshot");
         }
@@ -618,9 +622,10 @@ public class ZooKeeperServer implements SessionExpirer, 
ServerStats.Provider {
         restoreLatch = new CountDownLatch(1);
 
         try {
-            // set to the new zkDatabase
-            setZKDatabase(newZKDatabase);
-
+            synchronized (snapshotAndRestoreLock) {
+                // set to the new zkDatabase
+                setZKDatabase(newZKDatabase);
+            }
             // re-create SessionTrack
             createSessionTracker();
         } finally {