Thread out-of-synch 错误

debug一段代码的时候eclipse里出现：

    The out of synch notification in the debug view means that the code in the VM
is not the same as the code in the workspace.
At this time, our resolution is at the type level. If a type has changed in
the workspace but that change is not present in the stack frame displayed in
the debug view, we show that it is "out of synch." Stack frames may get out
of synch in three ways - the VM doesn't support hot code replace (HCR), a
particular attempt at HCR has failed (not all VMs support all redefinitions),
or the HCR succeeded but the VM was unable to pop the frame running old code.
This last case can occur, for example, when the type in which a main method
resides is successfully changed. The main method will display "out of synch"
because the VM cannot pop the main method from the stack until the program
exits.We cannot know what code is executing in a running thread, so the best that
we can do is to say that a running thread "may be out of synch" after an HCR
fails. That is, it may or may not be running the code which wasn't updated.

可能是机器内存太小的原因，解决方法，重新发布工程，不行就重启tomcat和eclipse。