Please kill your Server! Thanks, Customer Support



  • Hey guys,

    I just got an email from Customer-Support. (Un-?)fortunately I was only on CC, and I actually work for that company ;)
    (translated to english..)

     --------------------

    Hello Mr Right,



    You wrote:



    We created the requested Thread Dumps at todays load peaks. I already sent them to you .



    Unfortunately the File didn't contain any Thread-Dumps, only normal log messages from the server. However I sent you a wrong instruction by mistake. To create a Thread-Dump you have to use the command:



    kill -3 <pid>



    (NOT kill -9 ...)


    So please, if the load raises again use kill -3 th create the Thread-Dump. Excuse the wrong instruction!

    ----------------

     

    Merry X-mas,

    lupo

     

     



  • Welllllllll.... kill-9 will reduce the load on the server...



  • @snoofle said:

    Welllllllll.... kill-9 will reduce the load on the server...

     

    But it will significantly increase the load in the operator's pants.



  • So.. he will get a dump. Maybe just not the one he was asking for.



  • But it still won't have threads in it.  ...  Or at least one would hope not.



  • Maybe you need some fiber?



  • @Xyro said:

    But it still won't have threads in it.  ...  Or at least one would hope not.

    Mostly depends on what he eats.



  • @b-redeker said:

    Maybe you need some fiber?

    Optic one ?



  •  so.. what do you think is TRWTF here? The support telling the customer to kill -9 its server, or the admin at the customer site who blindly executes that command, not knowing what a kill -9 will do? :D

     (maybe once i'll tell him that "rm -rf / " will help with the problem of too much disk space usage... )



  • @lupo said:

    so.. what do you think is TRWTF here? The support telling the customer to kill
    -9 its server, or the admin at the customer site who blindly executes that
    command, not knowing what a kill -9 will do? :D
    Does it have to be an exclusive OR?



  • @PJH said:

    @lupo said:
    so.. what do you think is TRWTF here? The support telling the customer to kill
    -9 its server, or the admin at the customer site who blindly executes that
    command, not knowing what a kill -9 will do? :D
    Does it have to be an exclusive OR?
     

    correct answer, you've won another internet :)

     



  • @lupo said:

    kill -3 <pid>



    (NOT kill -9 ...)

    Depending on the software, kill -3 could still be quite problematic - the normal mnemonic name for that signal is QUIT.  Yes, the program will probably yield the desired thread dump.  However, unless they've specifically coded the app to not then exit, it will then exit.

    Depending on the platform, strace, dtrace, truss, or the equivalent can get you much better results: you not only get to know what threads are actively doing stuff that includes system calls, but you get to know a bunch of the system calls they're making, rather than an instantaneous snapshot in time.  Also, the process doesn't die.  (Of course, if they're making a *lot* of system calls, tracing the process could still cause as much of an outage as the kill -9...)

    Note that on some platforms, the trace programs available will report on library calls, either instead of or in addition to system calls.  If you're on Linux, you have super-user access, and your kernel's compiled for it, you may even be able to do kernel traces.


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