processhelp.pm: avoid potential endless loop, log more (Windows)

`pidwait()` is a function to wait for a PID to disappear from the list
of processes. On Windows change this function to:

- reduce the frequency of calling the external command `tasklist` to
  query the list of processes, including Windows-native ones, to 0.2s
  (from 0.01s).

- print a message when the wait exceeds 5 second marks.

- give up after 20 seconds of total wait, and print a message.

Also log `taskkill` commands to stdout instead of the log.

To potentially avoid hangs seen in CI, and make these spots more
transparent through the log.

Ref: #16840
Ref: #14854

Closes #16908

diff --git a/tests/processhelp.pm b/tests/processhelp.pm
index 01819295631488c2bab0c3fde08eb76bcfa1f9f6..283188c1a2a10df62527fc9fd372b9cbfe5657de 100644 (file)
--- a/tests/processhelp.pm
+++ b/tests/processhelp.pm
@@ -169,7 +169,7 @@ sub pidterm {
             if($^O ne 'MSWin32') {
                 # https://ss64.com/nt/taskkill.html
                 my $cmd = "taskkill -t -pid $pid >nul 2>&1";
-                logmsg "Executing: '$cmd'\n";
+                print "Executing: '$cmd'\n";
                 system($cmd);
                 return;
             }
@@ -194,7 +194,7 @@ sub pidkill {
             if($^O ne 'MSWin32') {
                 # https://ss64.com/nt/taskkill.html
                 my $cmd = "taskkill -f -t -pid $pid >nul 2>&1";
-                logmsg "Executing: '$cmd'\n";
+                print "Executing: '$cmd'\n";
                 system($cmd);
                 return;
             }
@@ -218,8 +218,18 @@ sub pidwait {
         if($flags == &WNOHANG) {
             return pidexists($pid)?0:$pid;
         }
+        my $start = time;
+        my $warn_at = 5;
         while(pidexists($pid)) {
-            portable_sleep(0.01);
+            if(time - $start > $warn_at) {
+                print "pidwait: still waiting for PID ", $pid, "\n";
+                $warn_at += 5;
+                if($warn_at > 20) {
+                    print "pidwait: giving up waiting for PID ", $pid, "\n";
+                    last;
+                }
+            }
+            portable_sleep(0.2);
         }
         return $pid;
     }