hama-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Edward J. Yoon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HAMA-971) An increment to a volatile field isn't atomic
Date Fri, 28 Aug 2015 13:17:45 GMT

    [ https://issues.apache.org/jira/browse/HAMA-971?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14718544#comment-14718544
] 

Edward J. Yoon commented on HAMA-971:
-------------------------------------

Hi, 

I looked at this code just now, and it seems that variables used within synchronized block.
I'm not sure whether this guarantees write safety. 

{code}
synchronized (this) {
  ...
  ++checkpointMessageCount;
  ...
}
{code}


> An increment to a volatile field isn't atomic
> ---------------------------------------------
>
>                 Key: HAMA-971
>                 URL: https://issues.apache.org/jira/browse/HAMA-971
>             Project: Hama
>          Issue Type: Bug
>          Components: bsp core
>            Reporter: JongYoon Lim
>            Priority: Minor
>
> I found a defect from FindBugs Analysis.
> {code}
> // AsyncRcvdMsgCheckpointImpl.java
> volatile private long checkpointMessageCount;
> ...
> ++checkpointMessageCount;
> {code}
> {code}
> // Server.java
> private volatile int rpcCount = 0; // number of outstanding rpcs
> ...
> rpcCount--;
> rpcCount++;
> {code}
> This code increments a volatile field. Increments of volatile fields aren't atomic. If
more than one thread is incrementing the field at the same time, increments could be lost.
> I think *AtomicInteger* and *AtomicLong* can be used instead of volatile fields. 



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message