Hi devs,
I am trying to fix https://issues.apache.org/jira/browse/AMBARI-4930 since it
is becoming a blocking issue for us. I am taking a look at the code and I am
seeing this locking pattern in ClusterImpl.java:
clusterGlobalLock.writeLock().lock();
try {
writeLock.lock();
try {
[…]
} finally {
writeLock.unlock();
}
} finally {
clusterGlobalLock.writeLock().unlock();
}
Both “clusterGlobalLock” and “writeLock” are declared as private instance
variables and both have the same type (ReentrantReadWriteLock), but
“clusterGlobalLock” is being exposed through the interface and other classes
are using it (for example, ServiceImpl.java). The part I don’t understand is
this pattern:
clusterGlobalLock.readLock().lock();
try {
writeLock.lock();
try {
[…]
} finally {
writeLock.unlock();
}
} finally {
clusterGlobalLock.readLock().unlock();
}
Why is the globalLock being locked on read but the internal writeLock being
used (instead of readLock)? If the method is changing the clusters value (for
example, “setClusterName”), why is it locking on read in “clusterGlobalLock”?
Thanks,
Ximo.
________________________________
Este mensaje se dirige exclusivamente a su destinatario. Puede consultar
nuestra política de envío y recepción de correo electrónico en el enlace
situado más abajo.
This message is intended exclusively for its addressee. We only send and
receive email on the basis of the terms set out at:
http://www.tid.es/ES/PAGINAS/disclaimer.aspx
