[ZOOKEEPER-666] Unsafe publication in client API

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.2
• Component/s: java client
• Assignee: Zili Chen
• Reporter: Martin Traverso
• Created: 10/Feb/10 23:53
• Updated: 24/Sep/23 03:58
• Resolved: 24/Sep/23 03:58

Description

The following code may result in a data race due to unsafe publication of a reference to "this". The call to cnxn.start() spawns threads that have access to the partially-constructed reference to the ZooKeeper object.

See http://www.ibm.com/developerworks/java/library/j-jtp0618.html for some background info.

public ZooKeeper(String connectString, int sessionTimeout, Watcher watcher)
    throws IOException
{
        .....
        cnxn = new ClientCnxn(connectString, sessionTimeout, this, watchManager);
        cnxn.start();
}

The obvious fix is to move the call to cnxn.start() into a separate start() method.

Issue Links

• is cloned by: ZOOKEEPER-837 cyclic dependency ClientCnxn, ZooKeeper
• is related to: ZOOKEEPER-835 Refactoring Zookeeper Client Code