test: prove that Fibers work if not calling Go

README.md

@@ -38,6 +38,7 @@ containing [PHP 8.2](https://www.php.net/releases/8.2/en.php) and most popular P
 * [Docker images](docs/docker.md)
 * [Compile from sources](docs/compile.md)
 * [Create static binaries](docs/static.md)
+* [Known issues](docs/known-issues.md)
 * [Demo app (Symfony) and benchmarks](https://github.com/dunglas/frankenphp-demo)
 * [Go library documentation](https://pkg.go.dev/github.com/dunglas/frankenphp)
 * [Contributing and debugging](CONTRIBUTING.md)

docs/known-issues.md

@@ -0,0 +1,32 @@
+# Known Issues
+
+## Fibers
+
+Calling PHP functions and language constructs that themselves call [cgo](https://go.dev/blog/cgo) in [Fibers](https://www.php.net/manual/en/language.fibers.php) is known to cause crashes.
+
+This issue [is being worked on by the Go project](https://github.com/golang/go/issues/62130).
+
+
+In the meantime, one solution is not to use constructs (like `echo`) and functions (like `header()`) that delegate to Go from inside Fibers.
+
+This code will likely crash because it uses `echo` in the Fiber:
+
+```php
+$fiber = new Fiber(function() {
+    echo 'In the Fiber'.PHP_EOL;
+    echo 'Still inside'.PHP_EOL;
+});
+$fiber->start();
+```
+
+Instead, return the value from the Fiber and use it outside:
+
+```php
+$fiber = new Fiber(function() {
+    Fiber::suspend('In the Fiber'.PHP_EOL));
+    Fiber::suspend('Still inside'.PHP_EOL));
+});
+echo $fiber->start();
+echo $fiber->resume();
+$fiber->resume();
+```

frankenphp_test.go

@@ -571,3 +571,20 @@ func ExampleServeHTTP() {
 	})
 	log.Fatal(http.ListenAndServe(":8080", nil))
 }
+
+func TestFiberNoCgo_module(t *testing.T) { testFiberNoCgo(t, &testOptions{}) }
+func TestFiberNonCgo_worker(t *testing.T) {
+	testFiberNoCgo(t, &testOptions{workerScript: "fiber-no-cgo.php"})
+}
+func testFiberNoCgo(t *testing.T, opts *testOptions) {
+	runTest(t, func(handler func(http.ResponseWriter, *http.Request), _ *httptest.Server, i int) {
+		req := httptest.NewRequest("GET", fmt.Sprintf("http://example.com/fiber-no-cgo.php?i=%d", i), nil)
+		w := httptest.NewRecorder()
+		handler(w, req)
+
+		resp := w.Result()
+		body, _ := io.ReadAll(resp.Body)
+
+		assert.Equal(t, string(body), fmt.Sprintf("Fiber %d", i))
+	}, opts)
+}

testdata/fiber-no-cgo.php

@@ -0,0 +1,12 @@
+<?php
+require_once __DIR__.'/_executor.php';
+
+return function() {
+    $fiber = new Fiber(function() {
+        Fiber::suspend('Fiber '.($_GET['i'] ?? ''));
+    });
+    echo $fiber->start();
+
+    $fiber->resume();
+};
+