dmvk commented on a change in pull request #17607:
URL: https://github.com/apache/flink/pull/17607#discussion_r742796681
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/zookeeper/ZooKeeperStateHandleStore.java
##########
@@ -154,54 +158,75 @@ public ZooKeeperStateHandleStore(
throws PossibleInconsistentStateException, Exception {
checkNotNull(pathInZooKeeper, "Path in ZooKeeper");
checkNotNull(state, "State");
-
final String path = normalizePath(pathInZooKeeper);
+ try {
+ try {
+ // Obtain the write-lock.
+
client.create().withMode(CreateMode.EPHEMERAL).forPath(getWriteLockPath(path));
+ } catch (KeeperException.NodeExistsException e) {
+ // There should always be a single JobMaster for each job, so
we should never
+ // encounter this.
+ throw new IllegalStateException(
+ "Write lock is already taken, which signals there are
multiple processing writing to the same path. This should never happen.",
+ e);
+ }
+ if (exists(path).isExisting()) {
+ throw new AlreadyExistException(
+ String.format("ZooKeeper node %s already exists.",
path));
+ }
+ return doAddAndLock(path, state);
+ } finally {
+ // Release the write-lock.
+ deleteIfExists(getWriteLockPath(path));
+ }
+ }
- RetrievableStateHandle<T> storeHandle = storage.store(state);
-
- byte[] serializedStoreHandle = serializeOrDiscard(storeHandle);
-
+ private RetrievableStateHandle<T> doAddAndLock(String path, T state)
throws Exception {
+ final RetrievableStateHandle<T> storeHandle = storage.store(state);
+ final byte[] serializedStoreHandle = serializeOrDiscard(storeHandle);
try {
writeStoreHandleTransactionally(path, serializedStoreHandle);
return storeHandle;
} catch (Exception e) {
if (indicatesPossiblyInconsistentState(e)) {
throw new PossibleInconsistentStateException(e);
}
-
- // in any other failure case: discard the state
+ // In case of any other failure, discard the state and rethrow the
exception.
storeHandle.discardState();
-
- // We wrap the exception here so that it could be caught in
DefaultJobGraphStore
- throw ExceptionUtils.findThrowable(e,
KeeperException.NodeExistsException.class)
- .map(
- nee ->
- new AlreadyExistException(
- "ZooKeeper node " + path + "
already exists.", nee))
- .orElseThrow(() -> e);
+ throw e;
}
}
// this method is provided for the sole purpose of easier testing
@VisibleForTesting
protected void writeStoreHandleTransactionally(String path, byte[]
serializedStoreHandle)
throws Exception {
- // Write state handle (not the actual state) to ZooKeeper. This is
expected to be
- // smaller than the state itself. This level of indirection makes sure
that data in
- // ZooKeeper is small, because ZooKeeper is designed for data in the
KB range, but
- // the state can be larger.
- // Create the lock node in a transaction with the actual state node.
That way we can
+ // Write state handle (not the actual state) to ZooKeeper. This is
expected to be smaller
+ // than the state itself. This level of indirection makes sure that
data in ZooKeeper is
+ // small, because ZooKeeper is designed for data in the KB range, but
the state can be
+ // larger. Create the lock node in a transaction with the actual state
node. That way we can
// prevent race conditions with a concurrent delete operation.
- client.inTransaction()
- .create()
- .withMode(CreateMode.PERSISTENT)
- .forPath(path, serializedStoreHandle)
- .and()
- .create()
- .withMode(CreateMode.EPHEMERAL)
- .forPath(getLockPath(path))
- .and()
- .commit();
+ while (true) {
+ try {
+ client.inTransaction()
+ .create()
+ .withMode(CreateMode.PERSISTENT)
+ .forPath(path, serializedStoreHandle)
+ .and()
+ .create()
+ .withMode(CreateMode.EPHEMERAL)
+ .forPath(getLockPath(path))
+ .and()
+ .commit();
+ break;
+ } catch (KeeperException.NodeExistsException e) {
+ // Transactions are not idempotent in the curator version
we're currently used, so
Review comment:
👍
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/zookeeper/ZooKeeperStateHandleStore.java
##########
@@ -154,54 +158,75 @@ public ZooKeeperStateHandleStore(
throws PossibleInconsistentStateException, Exception {
checkNotNull(pathInZooKeeper, "Path in ZooKeeper");
checkNotNull(state, "State");
-
final String path = normalizePath(pathInZooKeeper);
+ try {
+ try {
+ // Obtain the write-lock.
+
client.create().withMode(CreateMode.EPHEMERAL).forPath(getWriteLockPath(path));
+ } catch (KeeperException.NodeExistsException e) {
+ // There should always be a single JobMaster for each job, so
we should never
+ // encounter this.
+ throw new IllegalStateException(
+ "Write lock is already taken, which signals there are
multiple processing writing to the same path. This should never happen.",
Review comment:
👍
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
