ashutosh-bapat commented on a change in pull request #669: HIVE-21864:
LlapBaseInputFormat#closeAll() throws ConcurrentModificationException
URL: https://github.com/apache/hive/pull/669#discussion_r292923257
##########
File path:
llap-ext-client/src/java/org/apache/hadoop/hive/llap/LlapBaseInputFormat.java
##########
@@ -345,8 +346,11 @@ public static void close(String handleId) throws
IOException {
*/
public static void closeAll() {
LOG.debug("Closing all handles");
- for (String handleId : connectionMap.keySet()) {
+ Iterator<String> handleIds = connectionMap.keySet().iterator();
+ String handleId = null;
+ while (handleIds.hasNext()) {
try {
+ handleId = handleIds.next();
Review comment:
I looked up many web pages/blogs which discuss "removing an element from
HashMap while iterating over it". All of them suggest one common method i.e.
using an iterator. I saw using ArrayList somewhere, but that's not a common
suggestion. If the keySet() doesn't return all the keys at once to create the
ArrayList at once, which it shouldn't ideally, we may be removing a key which
the iterator is scanning, thus causing an exception.
Since at the end we will remove all the elements, one possible solution is
to close all the connections first by iterating over the Map and then call
clear() on the Map. This will still require us to refactor close() method as
suggested earlier.
----------------------------------------------------------------
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.
For queries about this service, please contact Infrastructure at:
[email protected]
With regards,
Apache Git Services
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
