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https://issues.apache.org/jira/browse/TWILL-61?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16399626#comment-16399626
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ASF GitHub Bot commented on TWILL-61:
-------------------------------------
Github user anew commented on a diff in the pull request:
https://github.com/apache/twill/pull/67#discussion_r174643542
--- Diff:
twill-zookeeper/src/main/java/org/apache/twill/zookeeper/ZKOperations.java ---
@@ -281,6 +286,73 @@ public void onFailure(Throwable t) {
return resultFuture;
}
+ /**
+ * Creates a ZK node of the given path. If the node already exists,
deletion of the node (recursively) will happen
+ * and the creation will be retried.
+ */
+ public static OperationFuture<String> createDeleteIfExists(final
ZKClient zkClient, final String path,
+ @Nullable
final byte[] data, final CreateMode createMode,
+ final boolean
createParent, final ACL...acls) {
+ final SettableOperationFuture<String> resultFuture =
SettableOperationFuture.create(path,
+
Threads.SAME_THREAD_EXECUTOR);
+ final List<ACL> createACLs = acls.length == 0 ?
ZooDefs.Ids.OPEN_ACL_UNSAFE : Arrays.asList(acls);
+ createNode(zkClient, path, data, createMode, createParent, createACLs,
new FutureCallback<String>() {
+
+ final FutureCallback<String> createCallback = this;
+
+ @Override
+ public void onSuccess(String result) {
+ // Create succeeded, just set the result to the resultFuture
+ resultFuture.set(result);
+ }
+
+ @Override
+ public void onFailure(final Throwable createFailure) {
+ // If create failed not because of the NodeExistsException, just
set the exception to the result future
+ if (!(createFailure instanceof
KeeperException.NodeExistsException)) {
+ resultFuture.setException(createFailure);
+ return;
+ }
+
+ // Try to delete the path
+ LOG.info("Node {}{} already exists. Deleting it and retry
creation", zkClient.getConnectString(), path);
+ Futures.addCallback(recursiveDelete(zkClient, path), new
FutureCallback<String>() {
+ @Override
+ public void onSuccess(String result) {
+ // If delete succeeded, perform the creation again.
+ createNode(zkClient, path, data, createMode, createParent,
createACLs, createCallback);
+ }
+
+ @Override
+ public void onFailure(Throwable t) {
+ // If deletion failed because of NoNodeException, fail the
result operation future
+ if (!(t instanceof KeeperException.NoNodeException)) {
+ createFailure.addSuppressed(t);
+ resultFuture.setException(createFailure);
+ return;
+ }
+
+ // If can't delete because the node no longer exists, just go
ahead and recreate the node
+ createNode(zkClient, path, data, createMode, createParent,
createACLs, createCallback);
+ }
+ }, Threads.SAME_THREAD_EXECUTOR);
+ }
+ });
+
+ return resultFuture;
+ }
+
+ /**
+ * Private helper method to create a ZK node based on the parameter. The
result of the creation is always
+ * communicate via the provided {@link FutureCallback}.
+ */
+ private static void createNode(ZKClient zkClient, String path, @Nullable
byte[] data,
+ CreateMode createMode, boolean
createParent,
+ Iterable<ACL> acls,
FutureCallback<String> callback) {
+ Futures.addCallback(zkClient.create(path, data, createMode,
createParent, acls),
+ callback, Threads.SAME_THREAD_EXECUTOR);
+ }
--- End diff --
yes, easier to understand and extracted into separate methods. Like it much
better now
> Second launch attempt of AM always failed
> -----------------------------------------
>
> Key: TWILL-61
> URL: https://issues.apache.org/jira/browse/TWILL-61
> Project: Apache Twill
> Issue Type: Bug
> Components: yarn
> Reporter: Terence Yim
> Assignee: Terence Yim
> Priority: Major
> Fix For: 0.5.0-incubating
>
>
> YARN would make multiple attempts to launch an application. Currently second
> or above attempts would always fail due to creation of /runId/state node in
> ZK fail (node exists) because runId is generated on client side and doesn't
> change between attempts.
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