[YARN-9349] When doTransition() method occurs exception, the log level practices are inconsistent

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.0, 2.8.5
• Fix Version/s: 3.3.0
• Component/s: nodemanager
• Labels: easyfix
• Assignee: Unassigned
• Reporter: Anuhan Torgonshar
• Created: 06/Mar/19 13:24
• Updated: 23/Oct/19 16:14
• Resolved: 16/Apr/19 23:55

Description

There are inconsistent log level practices when code catches InvalidStateTransitionException for doTransition() method.

**************WARN level******************
/**
  file path: hadoop-2.8.5-src\hadoop-yarn-project\hadoop-yarn\hadoop-yarn-server\hadoop-yarn-server-nodemanager\src\main\java\org\apache\hadoop\yarn\server\nodemanager\containermanager\application\ApplicationImpl.java
  log statement line number: 482
  log level:warn
**/
try {
   // queue event requesting init of the same app
   newState = stateMachine.doTransition(event.getType(), event);
} catch (InvalidStateTransitionException e) {
   LOG.warn("Can't handle this event at current state", e);
}

/**
  file path: hadoop-2.8.5-src\hadoop-yarn-project\hadoop-yarn\hadoop-yarn-server\hadoop-yarn-server-nodemanager\src\main\java\org\apache\hadoop\yarn\server\nodemanager\containermanager\localizer\LocalizedResource.java
  log statement line number: 200
  log level:warn
**/
try {
   newState = this.stateMachine.doTransition(event.getType(), event);
} catch (InvalidStateTransitionException e) {
   LOG.warn("Can't handle this event at current state", e);
}

/**
  file path: hadoop-2.8.5-src\hadoop-yarn-project\hadoop-yarn\hadoop-yarn-server\hadoop-yarn-server-nodemanager\src\main\java\org\apache\hadoop\yarn\server\nodemanager\containermanager\container\ContainerImpl.java
  log statement line number: 1156
  log level:warn
**/
try {
    newState =
    stateMachine.doTransition(event.getType(), event);
} catch (InvalidStateTransitionException e) {
    LOG.warn("Can't handle this event at current state: Current: ["
    + oldState + "], eventType: [" + event.getType() + "]", e);
}

**************ERROR level*****************
/**
file path: hadoop-2.8.5-src\hadoop-yarn-project\hadoop-yarn\hadoop-yarn-server\hadoop-yarn-server-resourcemanager\src\main\java\org\apache\hadoop\yarn\server\resourcemanager\rmapp\attempt\RMAppAttemptImpl.java
log statement line number:878
log level: error
**/
try {
   /* keep the master in sync with the state machine */
   this.stateMachine.doTransition(event.getType(), event);
} catch (InvalidStateTransitionException e) {
   LOG.error("App attempt: " + appAttemptID
   + " can't handle this event at current state", e);
   onInvalidTranstion(event.getType(), oldState);
}

/**
file path: hadoop-2.8.5-src\hadoop-yarn-project\hadoop-yarn\hadoop-yarn-server\hadoop-yarn-server-resourcemanager\src\main\java\org\apache\hadoop\yarn\server\resourcemanager\rmnode\RMNodeImpl.java
log statement line number:623
log level: error
**/
try {
   stateMachine.doTransition(event.getType(), event);
} catch (InvalidStateTransitionException e) {
   LOG.error("Can't handle this event at current state", e);
   LOG.error("Invalid event " + event.getType() + 
   " on Node " + this.nodeId);
}

.... 
//There are 8 similar code snippets with ERROR log level.

After had a look on whole project, I found that there are 8 similar code snippets assgin the ERROR level, when doTransition() ocurrs InvalidStateTransitionException. And there are just 3 places choose  the WARN level when in same situations. Therefor, I think these 3 log statements should be assigned ERROR level to keep consistent with other code snippets.