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From rakeshadr <...@git.apache.org>
Subject [GitHub] zookeeper pull request #254: ZOOKEEPER-2775: ZK Client not able to connect w...
Date Thu, 18 May 2017 10:00:05 GMT
Github user rakeshadr commented on a diff in the pull request:

    https://github.com/apache/zookeeper/pull/254#discussion_r117207576
  
    --- Diff: src/java/main/org/apache/zookeeper/ClientCnxn.java ---
    @@ -1054,6 +1054,8 @@ private void sendPing() {
             private boolean saslLoginFailed = false;
     
             private void startConnect() throws IOException {
    +            // initializing it for new connection
    +            saslLoginFailed = false;
    --- End diff --
    
    Thanks @arshadmohammad  for the details.
    
    yes, only `SendThread` is updating the flag. But, during sasl login retries period, the
flag status will be checked by `tunnelAuthInProgress()` packet processing thread, so multiple
threads are accessing the flag. The code looks little tricky and `zooKeeperSaslClient `null
value represents auth in progress. I'm almost OK with the change and trying another attempt
to avoid any compatibility issues to the users as this would go to stable branches:-). 
    
    Earlier the behavior was, once the flag updated to flase, `tunnelAuthInProgress` function
would return false always. Now, with the proposed fix, sometimes it would return false and
sometimes it would return true, right? Will this results in any consistency issues later?
    
    Assume  a case, where successful login takes several retries.
    (1) Immediately after the login failure the flag will be false. During this time `tunnelAuthInProgress()
` function returns false to the callers.
    (2) Assume, `startConnect()` retries started. During this time, `tunnelAuthInProgress()
` function returns true to the callers.
    
    My previous suggestion was to avoid this situation and consistently `tunnelAuthInProgress()`
function return false until the next successful login. Does this makes sense to you?
    
    @hanm, welcome your thoughts. Thanks!


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