Deadlock detection in Java

Question

Long time ago, I saved a sentence from a Java reference book: \"Java has no mechanism to handle deadlock. it won\'t even know deadlock occurred.\" (Head First Java 2nd E

Answer 1

Java can detect deadlocks (although not at run-time, it can still diagnose and report it).

For example, when using a slightly modified version of 'Saurabh M. Chande' code bellow (changed it to Java and added some timing to guarantee a lock on each run). Once you run it and it deadlocks, if you type:

kill -3 PID   # where 'PID' is the Linux process ID

It will generate a stack dump, which will include the following information:

Found one Java-level deadlock:
=============================
"Thread-0":
     waiting to lock monitor 0x08081670 (object 0x7f61ddb8, a Deadlock$A),
     which is held by "main"
"main":
      waiting to lock monitor 0x080809f0 (object 0x7f61f3b0, a Deadlock$B),
      which is held by "Thread-0"