[YARN-3364] Clarify Naming of yarn.client.nodemanager-connect.max-wait-ms and yarn.resourcemanager.connect.max-wait.ms

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Component/s: yarn
• Assignee: Unassigned
• Reporter: Andrew Johnson
• Created: 18/Mar/15 13:56
• Updated: 18/Mar/15 14:36
• Resolved: 18/Mar/15 14:36

Description

I encountered an issue recently where the ApplicationMaster for MapReduce jobs would spend hours attempting to connect to a node in my cluster that had died due to a hardware fault. After debugging this, I found that the yarn.client.nodemanager-connect.max-wait-ms property did not behave as I had expected. Based on the name I had thought this would set a maximum time limit for attempting to connect to a NodeManager. The code in org.apache.hadoop.yarn.client.NMProxy corroborated this thought - it used a RetryUpToMaximumTimeWithFixedSleep policy when a ConnectTimeoutException was thrown, as it was in my case with a dead node.

However, the RetryUpToMaximumTimeWithFixedSleep policy doesn't actually set a time limit, but instead divides the maximum time by the sleep period to set a total number of retries, regardless of how long those retries take. As such I was seeing the ApplicationMaster spend much longer attempting to make a connection than I had anticipated.

The yarn.resourcemanager.connect.max-wait.ms would have the same behavior. These properties would be better named like yarn.client.nodemanager-connect.max.retries and yarn.resourcemanager.connect.max.retries to better align with the actual behavior.

Issue Links

• duplicates: HADOOP-11398 RetryUpToMaximumTimeWithFixedSleep needs to behave more accurately