BSPMaster - job ID counter is not read and updated atomically
-------------------------------------------------------------
Key: HAMA-307
URL: https://issues.apache.org/jira/browse/HAMA-307
Project: Hama
Issue Type: Bug
Reporter: Filipe Manana
Attachments: hama-307.patch
The nextJobId (int attribute) in BSPMaster is not read and updated atomically,
therefore it's possible that concurrent requests get the same job ID and/or
cause the job ID to not get incremented by the proper quantity.
The following simple patch fixes it.
Notice:
I changed the type from int to Integer.
This is to avoid doing the following in getNewJobId():
int id;
synchronized (this) {
id = nextJobId++;
}
the instance (referenced by this) is synchronized in many places in BSPMaster,
so by making nextJobId an Integer (object), we can synchronize on it, reducing
contention times:
private Integer nextJobId = Integer.valueOf(1);
public BSPJobID getNewJobId() throws IOException {
int id;
synchronized (nextJobId) {
id = nextJobId;
nextJobId = Integer.valueOf(id + 1);
}
return new BSPJobID(this.masterIdentifier, id);
}
cheers
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
