Detect signaled parallel workers

src/Build/ParallelEntryWriter.php

@@ -21,7 +21,6 @@
 use function function_exists;
 use function min;
 use function pcntl_fork;
-use function pcntl_wexitstatus;
 use function pcntl_waitpid;
 
 final readonly class ParallelEntryWriter
@@ -126,15 +125,19 @@ private function writeParallel(SiteConfig $siteConfig, array $tasks, string $con
         }
 
         $failed = false;
+        $failure = null;
         foreach ($pids as $pid) {
             pcntl_waitpid($pid, $status);
-            if (pcntl_wexitstatus($status) !== 0) {
+            try {
+                WorkerProcessStatus::assertSucceeded($pid, $status);
+            } catch (RuntimeException $e) {
                 $failed = true;
+                $failure ??= $e;
             }
         }
 
         if ($failed) {
-            throw new RuntimeException('One or more worker processes failed');
+            throw new RuntimeException('One or more worker processes failed.', previous: $failure);
         }
     }
 

src/Build/ParallelTaskRunner.php

@@ -16,7 +16,6 @@
 use function mkdir;
 use function min;
 use function pcntl_fork;
-use function pcntl_wexitstatus;
 use function pcntl_waitpid;
 use function rmdir;
 use function sys_get_temp_dir;
@@ -72,9 +71,7 @@ public function run(array $tasks, int $workerCount, callable $taskRunner, int $m
 
             foreach ($pids as $pid) {
                 pcntl_waitpid($pid, $status);
-                if (pcntl_wexitstatus($status) !== 0) {
-                    throw new RuntimeException('One or more worker processes failed');
-                }
+                WorkerProcessStatus::assertSucceeded($pid, $status);
             }
 
             $count = 0;

src/Build/WorkerProcessStatus.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace YiiPress\Build;
+
+use RuntimeException;
+
+use function function_exists;
+use function pcntl_wexitstatus;
+use function pcntl_wifexited;
+use function pcntl_wifsignaled;
+use function pcntl_wtermsig;
+use function sprintf;
+
+final class WorkerProcessStatus
+{
+    public static function assertSucceeded(int $pid, int $status): void
+    {
+        if (function_exists('pcntl_wifexited') && pcntl_wifexited($status)) {
+            $exitCode = pcntl_wexitstatus($status);
+            if ($exitCode === 0) {
+                return;
+            }
+
+            throw new RuntimeException(sprintf('Worker process %d exited with code %d.', $pid, $exitCode));
+        }
+
+        if (function_exists('pcntl_wifsignaled') && pcntl_wifsignaled($status)) {
+            throw new RuntimeException(sprintf(
+                'Worker process %d was terminated by signal %d.',
+                $pid,
+                pcntl_wtermsig($status),
+            ));
+        }
+
+        throw new RuntimeException(sprintf('Worker process %d did not exit normally.', $pid));
+    }
+}

tests/Unit/Build/ParallelEntryWriterTest.php

@@ -17,11 +17,14 @@
 use PHPUnit\Framework\TestCase;
 use RecursiveDirectoryIterator;
 use RecursiveIteratorIterator;
+use RuntimeException;
 use SplFileInfo;
 
 use function PHPUnit\Framework\assertFileExists;
 use function PHPUnit\Framework\assertSame;
 use function PHPUnit\Framework\assertStringContainsString;
+use function getmypid;
+use function posix_kill;
 use function sys_get_temp_dir;
 
 final class ParallelEntryWriterTest extends TestCase
@@ -102,12 +105,44 @@ public function testWriteFallsBackToSequentialForTinyTaskSet(): void
         assertStringContainsString('Only Post', (string) file_get_contents($tasks[0]['filePath']));
     }
 
-    private function createPipeline(): ContentProcessorPipeline
+    public function testWriteFailsWhenParallelWorkerIsTerminatedBySignal(): void
+    {
+        $tasks = [];
+        for ($i = 0; $i < 128; $i++) {
+            $title = $i === 0 ? 'Kill Worker' : 'Post ' . $i;
+            $entry = $this->createEntry('entry-' . $i, $title);
+            $tasks[] = [
+                'entry' => $entry,
+                'filePath' => $this->outputDir . '/blog/entry-' . $i . '/index.html',
+                'permalink' => '/blog/entry-' . $i . '/',
+            ];
+        }
+
+        $writer = new ParallelEntryWriter($this->createPipeline(killOnTitle: 'Kill Worker'), $this->createTemplateResolver());
+
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('One or more worker processes failed.');
+
+        try {
+            $writer->write($this->createSiteConfig(), $tasks, $this->contentDir, 2);
+        } catch (RuntimeException $e) {
+            assertStringContainsString('terminated by signal', (string) $e->getPrevious()?->getMessage());
+            throw $e;
+        }
+    }
+
+    private function createPipeline(string $killOnTitle = ''): ContentProcessorPipeline
     {
         return new ContentProcessorPipeline(
-            new class () implements ContentProcessorInterface {
+            new readonly class ($killOnTitle) implements ContentProcessorInterface {
+                public function __construct(private string $killOnTitle) {}
+
                 public function process(string $content, Entry $entry): string
                 {
+                    if ($entry->title === $this->killOnTitle) {
+                        posix_kill(getmypid(), \SIGKILL);
+                    }
+
                     return '<p>' . $content . '</p>';
                 }
             },

tests/Unit/Build/ParallelTaskRunnerTest.php

@@ -6,6 +6,7 @@
 
 use YiiPress\Build\ParallelTaskRunner;
 use PHPUnit\Framework\TestCase;
+use RuntimeException;
 
 use function array_unique;
 use function count;
@@ -15,6 +16,7 @@
 use function is_file;
 use function PHPUnit\Framework\assertNotFalse;
 use function PHPUnit\Framework\assertSame;
+use function posix_kill;
 use function sys_get_temp_dir;
 use function uniqid;
 use function unlink;
@@ -67,4 +69,25 @@ static function () use ($pidFile): int {
             }
         }
     }
+
+    public function testRunFailsWhenWorkerIsTerminatedBySignal(): void
+    {
+        $runner = new ParallelTaskRunner();
+
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('terminated by signal');
+
+        $runner->run(
+            [1, 2],
+            2,
+            static function (int $task): int {
+                if ($task === 1) {
+                    posix_kill(getmypid(), \SIGKILL);
+                }
+
+                return 1;
+            },
+            minTasksPerWorker: 1,
+        );
+    }
 }