[HDFS-dev] [jira] [Created] (HDFS-2103) Read lock must be released before acquiring a write lock

Read lock must be released before acquiring a write lock
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Key: HDFS-2103
URL: https://issues.apache.org/jira/browse/HDFS-2103
Project: Hadoop HDFS
Issue Type: Bug
Affects Versions: 0.23.0
Reporter: Bharath Mundlapudi
Assignee: Bharath Mundlapudi
Fix For: 0.23.0


In FSNamesystem.getBlockLocationsUpdateTimes function, we have the following code:

{code}
for (int attempt = 0; attempt < 2; attempt++) {
if (attempt == 0) { // first attempt is with readlock
readLock();
} else { // second attempt is with write lock
writeLock(); // writelock is needed to set accesstime
}

...

if (attempt == 0) {
continue;
}
{code}

In the above code, readLock is acquired in attempt 0 and if the execution enters in the continue block, then it tries to acquire writeLock before releasing the readLock.