Changeset 31699

Timestamp:

2017-05-24T19:59:51+12:00 (7 years ago)

Author:

ak19

Message:

Mac testing of SafeProcess: everything else worked (User comments, documenting editing if server not run from GLI), but discovered issues with canceling a build in progress from GLI. Found out that on Mac, with full-import (but not full-buildcol), subprocesses that are launched by a process don't get terminated when the process is killed. This was a problem in versions of GS before SafeProcess, such as in gs version 3.08. Running the scripts from the commandline had weird behaviour too, but from the cmdline, not only did terminating full-import with a TERM or KILL signal not kill subprocesses (like import.pl) but terminating full-buildcol.pl did not kill subprocesses now either (like buildcol.pl). So resorted to attempting a solution from GLI's Java code as for Windows. First wanted to do a recursive terminate, as for windows, by obtaining the childpids of every process using cmd: pgrep -P pid. However, while full-import.pl would return childpids when built from GLI, full-buildcol had no childpids to return. Mystifyingly, from the cmdline both would return childpids. Then sought and attempted several alternatives that are supposed to kill an entire process tree on Unix systems, but settled on the only one that worked on the mac: pkill -TERM -P pid.

File:

• main/trunk/gli/src/org/greenstone/gatherer/util/SafeProcess.java (modified) (4 diffs)

main/trunk/gli/src/org/greenstone/gatherer/util/SafeProcess.java

@@ -751 +751 @@
 }
 
+// https://stackoverflow.com/questions/8533377/why-child-process-still-alive-after-parent-process-was-killed-in-linux
+// Didn't work for when build scripts run from GLI: kill -TERM -pid
+// but the other suggestion did work: pkill -TERM -P pid did work
+// https://unix.stackexchange.com/questions/117227/why-pidof-and-pgrep-are-behaving-differently
+// https://unix.stackexchange.com/questions/67635/elegantly-get-list-of-children-processes
+// https://stackoverflow.com/questions/994033/mac-os-x-quickest-way-to-kill-quit-an-entire-process-tree-from-within-a-cocoa-a
+// https://unix.stackexchange.com/questions/132224/is-it-possible-to-get-process-group-id-from-procŧŧ
+
+/**
+ * On Unix, will kill the process denoted by processID and any subprocessed this launched. Tested on a Mac.
+ * @force if true will send the -KILL (-9) signal, which may result in abrupt termination
+ * if false, will send the -TERM (-15) signal, which will allow cleanup before termination
+ * @killEntireTree if false, will terminate only the process denoted by processID, otherwise all descendants too.
+ * @return true if running the kill process returned an exit value of 0
+ * 
+*/
+static boolean killUnixProcessTreeWithID(long processID, boolean force, boolean killEntireTree) {
+    // Kill signals, their names and numerical equivalents: http://www.faqs.org/qa/qa-831.html
+
+    /*
+    String cmd = force ? "kill -KILL" : "kill -TERM"; // kill -15 vs kill -9
+    // https://stackoverflow.com/questions/8533377/why-child-process-still-alive-after-parent-process-was-killed-in-linux
+    cmd += killEntireTree ? " -" : " "; // prefix hyphen to pid to kill all subprocesses launched by pid
+    cmd = cmd + processID;
+    */
+
+    String cmd = "pkill -TERM -P " + processID;
+    if(force) {
+    cmd = "pkill -KILL -P " + processID;
+    } 
+
+    SafeProcess proc = new SafeProcess(cmd);
+    int exitValue = proc.runProcess();
+    if(exitValue != 0) {
+    log("@@@ Not able to successfull terminate process, got exitvalue " + exitValue);
+    log("@@@ Got output " + proc.getStdOutput()); 
+    log("@@@ Got err output " + proc.getStdError());
+    // caller can try again with kill -KILL, by setting force parameter to true
+    return false;
+    } else {
+    if(force) {
+        log("@@@ Successfully sent SIGKILL to unix process tree rooted at " + processID);
+    } else { 
+        log("@@@ Successfully sent SIGTERM to unix process tree rooted at " + processID);
+    }
+    return true;
+    }    
+}
+
+/** UNUSED. Kills only the process represented by the processID.
+ * @force if true will send the -KILL (-9) signal, which may result in abrupt termination
+ * if false, will send the -TERM (-15) signal, which will allow cleanup before termination
+ * @return true if running the kill process returned an exit value of 0
+*/
+static boolean killUnixProcessWithID(long processID, boolean force) {
+    // Kill signals, their names and numerical equivalents: http://www.faqs.org/qa/qa-831.html
+    String cmd = force ? "kill -KILL" : "kill -TERM"; // kill -15 vs kill -9
+    cmd = cmd + " " + processID;
+
+    SafeProcess proc = new SafeProcess(cmd);
+    int exitValue = proc.runProcess();
+    if(exitValue != 0) {
+    log("@@@ Not able to successfull terminate process, got exitvalue " + exitValue);
+    log("@@@ Got output " + proc.getStdOutput()); 
+    log("@@@ Got err output " + proc.getStdError());
+    // caller can try again with kill -KILL, by setting force parameter to true
+    return false;
+    } else {
+    if(force) {
+        log("@@@ Successfully sent SIGKILL to unix process " + processID);
+    } else { 
+        log("@@@ Successfully sent SIGTERM to unix process " + processID);
+    }
+    return true;
+    }    
+}
+
 
 // On linux and mac, p.destroy() suffices to kill processes launched by p as well.
@@ -758 +835 @@
     log("### in SafeProcess.destroyProcess(Process p)");
 
+    String osName = Utility.getOSdirName();
+
     // If it isn't windows, process.destroy() terminates any child processes too
-    if(!Utility.isWindows()) {
+    if(osName.equals("linux")) {
     p.destroy();
     return;
-    }   
-    
+    }
+
+    if(osName.equals("darwin")) {
+    long pid = SafeProcess.getProcessID(p);
+    /*
+    // On Macs (all Unix?) can't get the child processes of a process once it's been destroyed
+    macTerminateSubProcessesRecursively(pid, p); // pid, true)  
+    */
+    
+    if(pid == -1) {
+        p.destroy(); // at minimum, will have no effect if the process had already terminated 
+    } else {
+        boolean forceKill = false;
+        boolean killEntireProcessTree = true;
+        if(!killUnixProcessTreeWithID(pid, !forceKill, killEntireProcessTree)) { // send sig TERM (kill -15 or kill -TERM)
+        killUnixProcessTreeWithID(pid, forceKill, killEntireProcessTree); // send sig KILL (kill -9 or kill -KILL)
+        }
+    }
+
+    return;
+    }
+    
+    // else we're on windows:
+
     if(!SafeProcess.isAvailable("wmic")) {
     log("wmic, used to kill subprocesses, is not available. Unable to terminate subprocesses...");
@@ -784 +885 @@
     }
     
+}
+
+
+// UNUSED
+// But if this method is needed, then need to parse childpids printed by "pgrep -P pid" and write recursive step
+// The childpids are probably listed one per line, see https://unix.stackexchange.com/questions/117227/why-pidof-and-pgrep-are-behaving-differently
+private static void macTerminateSubProcessesRecursively(long parent_pid, Process p) { //boolean isTopLevelProcess) {
+    log("@@@ Attempting to terminate mac process recursively");
+
+    // https://unix.stackexchange.com/questions/67635/elegantly-get-list-of-children-processes
+    SafeProcess proc = new SafeProcess("pgrep -P "+parent_pid);
+    int exitValue = proc.runProcess();
+    String stdOutput = proc.getStdOutput();
+    String stdErrOutput = proc.getStdError();
+
+    // now we have the child processes, can terminate the parent process
+    if(p != null) { // top level process, can just be terminated the java way with p.destroy()
+    p.destroy();
+    } else {
+    // get rid of process with current pid
+    if(!SafeProcess.killUnixProcessWithID(parent_pid, false)) { // send kill -TERM, kill -15
+        SafeProcess.killUnixProcessWithID(parent_pid, true); // send kill -9, kill -KILL
+    }
+    }
+    
+    /*
+    // get rid of any process with current pid
+    if(!isTopLevelProcess && !SafeProcess.killUnixProcessWithID(parent_pid, false)) { // send kill -TERM, kill -15
+    SafeProcess.killUnixProcessWithID(parent_pid, true); // send kill -9, kill -KILL
+    }
+    */
+
+    if(stdOutput.trim().equals("") && stdErrOutput.trim().equals("") && exitValue == 1) {
+    log("No child processes");
+    // we're done
+    return;
+    } else {
+    log("Got childpids on STDOUT: " + stdOutput);
+    log("Got childpids on STDERR: " + stdErrOutput);
+    }
 }
 
@@ -812 +953 @@
     p.destroy();
     } else { // terminate windows way       
-    SafeProcess.killWinProcessWithID(parent_pid); // get rid off current pid        
+    SafeProcess.killWinProcessWithID(parent_pid); // get rid of process with current pid        
     }