To avoid data corruption in multithreaded Java programs, shared data must be protected from concurrent modifications and accesses. This can be performed at the object level by using synchronized methods or blocks, or by using dynamic lock objects. However, excessive use of locking may result in deadlocks (See CON08-J. Do not call alien methods that synchronize on the same objects as any callers in the execution chain).
To avoid deadlock, locks should be acquired and released in the same order and synchronization should be limited to where it is absolutely necessary. For instance, to avoid deadlocks in an applet, the paint(), dispose(), stop(), and destroy() methods should not be synchronized because they are always called and used from dedicated threads.
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"The Java programming language neither prevents nor requires detection of deadlock conditions." \[[JLS 05|AA. Java References#JLS 05]\]. Deadlocks can arise when two or more threads request and release locks in different orders. Therefore, to avoid deadlock, locks should be acquired and released in the same order and synchronization should be limited to where it is absolutely necessary. For instance, to avoid deadlocks in an applet, the {{paint()}}, {{dispose()}}, {{stop()}}, and {{destroy()}} methods should not be synchronized because they are always called and used from dedicated threads. |
Noncompliant Code Example
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