jstack and the target output

Alan Bateman Alan.Bateman at oracle.com
Thu Nov 21 05:14:54 PST 2013

On 21/11/2013 13:06, Piotr Bzdyl wrote:
> Hello,
> I wasn't sure which OpenJDK mailing list I should choose for my 
> question. As I have issues with jstack SA related group seemed the 
> best place.
> I have the following issue:
> On console one (let's call it pts/1) I start a sample java app (let's 
> say its pid is 1234). On another console (pts/2) I execute:
> jstack 1234
> As a result pts/2 displays:
> 1234: Unable to open socket file: target process not responding or 
> HotSpot VM not loaded
> The -F option can be used when the target process is not responding
> And on pts/1 I see the thread dump printed. I would rather expect that 
> the thread dump will be displayed on pts/2 and nothing will be printed 
> to pts/1. I tried to use different versions of OpenJDK but the result 
> was always the same.
> Could you provide me any hints what might be wrong?
> Best regards,
> Piotr
Are pts/1 and pts/2 the same user? Alternatively, any special options to 
the target VM that disables the attach mechanism?

In any case, I suspect the reason that pts/1 is print the stack trace is 
that the mechanism to start the attach mechanism in the target VM 
requires signalling the target VM with SIGQUIT, the same signal that is 
used to get a VM to do a thread dump to its own stdout.


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