Spring boot clean up on sigkill

Question

I am running a SpringBoot Application. I have added some cleanup action using @PreDestroy annotation. When I terminate the process using SIGTERM that is kill ${PID} of tomcat, it performs all the cleanup tasks by calling method marked with @PreDestroy. However, When I use SIGKILL i.e kill -9 ${PID} of tomcat , the clean up is not performed.

Is there any way to make the application perform all the pre destruction work when it is terminated using SIGKILL?

Answer 1

No, there is not. Regular kill waits for the process to exit while kill -9 does not and kills it immediately. What is important is that the signals SIGKILL and SIGSTOP cannot be caught, blocked, or ignored. man 7 signal shows a short summary of what each signal means:

   Signal     Value     Action   Comment
   ──────────────────────────────────────────────────────────────────────
   SIGHUP        1       Term    Hangup detected on controlling terminal
                                 or death of controlling process
   SIGINT        2       Term    Interrupt from keyboard
   SIGQUIT       3       Core    Quit from keyboard
   SIGILL        4       Core    Illegal Instruction
   SIGABRT       6       Core    Abort signal from abort(3)
   SIGFPE        8       Core    Floating-point exception
   SIGKILL       9       Term    Kill signal
   SIGSEGV      11       Core    Invalid memory reference
   SIGPIPE      13       Term    Broken pipe: write to pipe with no
                                 readers; see pipe(7)
   SIGALRM      14       Term    Timer signal from alarm(2)
   SIGTERM      15       Term    Termination signal
   SIGUSR1   30,10,16    Term    User-defined signal 1
   SIGUSR2   31,12,17    Term    User-defined signal 2
   SIGCHLD   20,17,18    Ign     Child stopped or terminated
   SIGCONT   19,18,25    Cont    Continue if stopped
   SIGSTOP   17,19,23    Stop    Stop process
   SIGTSTP   18,20,24    Stop    Stop typed at terminal
   SIGTTIN   21,21,26    Stop    Terminal input for background process
   SIGTTOU   22,22,27    Stop    Terminal output for background process