[
https://issues.apache.org/jira/browse/FLINK-909?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14090464#comment-14090464
]
ASF GitHub Bot commented on FLINK-909:
--------------------------------------
Github user uce commented on a diff in the pull request:
https://github.com/apache/incubator-flink/pull/91#discussion_r15982053
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/iterative/concurrent/SuperstepKickoffLatch.java
---
@@ -0,0 +1,65 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.iterative.concurrent;
+
+public class SuperstepKickoffLatch {
+
+ private final Object monitor = new Object();
+
+ private int superstepNumber = 1;
+
+ private boolean terminated;
+
+ public void triggerNextSuperstep() {
+ synchronized (monitor) {
+ if (terminated) {
+ throw new IllegalStateException("Already
teriminated.");
--- End diff --
typo: terminated
> Pitfall due to additional superstep after the iteration has stopped
> -------------------------------------------------------------------
>
> Key: FLINK-909
> URL: https://issues.apache.org/jira/browse/FLINK-909
> Project: Flink
> Issue Type: Bug
> Reporter: GitHub Import
> Assignee: Markus Holzemer
> Labels: github-import
> Fix For: pre-apache
>
>
> Currently, after an iteration has exceeded the maximum number of iterations,
> all tasks are started again for an additional superstep during which they are
> stopped. This works if a tasks only waits for dynamic input. However, in the
> case where one has a task, e.g. a coGroup operation, which gets dynamic and
> static input the execution is not blocked. This can then lead to erroneous
> behaviour which the user is not aware of.
> I had this problem implementing ALS. Here one has a loop which gets as
> dynamic input matrix columns and as static input matrix entries. The columns
> and the entries are used to construct a matrix which represents a system of
> linear equations. If the set of columns are empty, then the matrix is
> singular and thus not solvable. During the additional superstep the task
> won't receive any columns but would still try to solve the now singular
> matrix.
> It would be good to finish the iteration without initiating this additional
> superstep.
> ---------------- Imported from GitHub ----------------
> Url: https://github.com/stratosphere/stratosphere/issues/909
> Created by: [tillrohrmann|https://github.com/tillrohrmann]
> Labels:
> Created at: Thu Jun 05 17:50:17 CEST 2014
> State: open
--
This message was sent by Atlassian JIRA
(v6.2#6252)
