Fixed bug #38441: CPU usage goes to 100% if load is higher than --load at first job.

src/parallel

@@ -1297,15 +1297,18 @@ sub start_more_jobs {
             }
         }
 
+	my $sleep = 0.0001; # 0.01 ms - better performance on highend
         for my $sshlogin (values %Global::host) {
             debug("Running jobs before on ".$sshlogin->string().": ".$sshlogin->jobs_running()."\n");
 	    while ($sshlogin->jobs_running() < $sshlogin->max_jobs_running()) {
 		if($opt::load and $sshlogin->loadavg_too_high()) {
 		    # The load is too high or unknown
+		    $sleep = ::reap_usleep($sleep);
 		    next;
 		}
 		if($opt::noswap and $sshlogin->swapping()) {
 		    # The server is swapping
+		    $sleep = ::reap_usleep($sleep);
 		    next;
 		}
 		if($sshlogin->too_fast_remote_login()) {
@@ -2482,7 +2485,7 @@ sub loadavg {
         # load average: 0.76, 1.53, 1.45
         if($uptime_out =~ /load averages?: (\d+.\d+)/) {
             $self->{'loadavg'} = $1;
-            ::debug("New loadavg: ".$self->{'loadavg'});
+            ::debug("New loadavg: ".$self->{'loadavg'}."\n");
         } else {
 	    ::die_bug("loadavg_invalid_content: $uptime_out");
 	}

src/parallel.texi

@@ -1645,6 +1645,14 @@ treated as the relative path to your home dir. This means that if your
 home dir is different on remote computers (e.g. if your login is
 different) the relative path will still be relative to your home dir.
 
+To see the difference try:
+
+@strong{parallel -S server pwd ::: ""}
+
+@strong{parallel --wd . -S server pwd ::: ""}
+
+@strong{parallel --wd ... -S server pwd ::: ""}
+
 @item @strong{--wait}
 @anchor{@strong{--wait}}
 

testsuite/tests-to-run/parallel-local2.sh

@@ -1,13 +1,36 @@
 #!/bin/bash
 
+highload ()
+{
+  # Force load > #cpus
+  CPUS=$(parallel --number-of-cores)
+  seq 0 0.1 $CPUS | nice nice parallel -j0 timeout 50 burnP6 2>/dev/null &
+  perl -e 'do{$a=`uptime`} while($a=~/average: *(\S+)/ and $1 < '$CPUS')'
+  # Load is now > $CPUS
+  # Kill off burnP6 and the parent parallel
+  kill %1; sleep 0.1; kill %1; killall burnP6; sleep 0.3; kill -9 %1 2>/dev/null
+}
+
+highload 2>/dev/null
+
+cat <<'EOF' | parallel -j0 -k -L1
+echo "bug #38441: CPU usage goes to 100% if load is higher than --load at first job"
+/usr/bin/time -f %e parallel --load 100% true ::: a 2>&1 | 
+  perl -ne '$_ > 1 and print "More than 1 secs wall clock: OK\n"'
+
+/usr/bin/time -f %U parallel --load 100% true ::: a 2>&1 | 
+  perl -ne '$_ < 1 and print "Less than 1 secs user time: OK\n"'
+
 echo '### Test slow arguments generation - https://savannah.gnu.org/bugs/?32834'
-seq 1 3 | parallel -j1 "sleep 2; echo {}" | parallel -kj2 echo
+  seq 1 3 | parallel -j1 "sleep 2; echo {}" | parallel -kj2 echo
 
 echo '### Test too slow spawning'
-killall -9 burnP6 2>/dev/null
+# Let the commands below run during high load
 seq `parallel --number-of-cores` | parallel -j200% -N0 timeout -k 25 26 burnP6 & 
-sleep 1
+  sleep 1; 
-seq 1 1000 |
+  seq 1 1000 | stdout nice nice  parallel -s 100 -uj0 true | 
-stdout nice nice  parallel -s 100 -uj0 true |
+  perl -pe '/parallel: Warning: Starting \d+ processes took/ and do {close STDIN; `killall -9 burnP6`; print "OK\n"; exit }'
-perl -pe '/parallel: Warning: Starting \d+ processes took/ and do {close STDIN; `killall -9 burnP6`; print "OK\n"; exit }'
+EOF
+
+# Make sure we got all the burnP6 killed
 killall -9 burnP6 2>/dev/null

testsuite/wanted-results/parallel-local2

@@ -1,3 +1,6 @@
+bug #38441: CPU usage goes to 100% if load is higher than --load at first job
+More than 1 secs wall clock: OK
+Less than 1 secs user time: OK
 ### Test slow arguments generation - https://savannah.gnu.org/bugs/?32834
 1
 2