[feature] Write data to file on SIGINT unless specified

README.md

@@ -63,6 +63,22 @@ The visualizer is WIP, you are welcome to contribute with major changes to the e
 * Red: time spent executing the callback code (blocking).
 * Black: when the async request was made.
 
+## SIGINT (Ctrl-C) Behavior
+
+To help debug process that may not have a defined exit, or may have a
+problematic handle keeping them open, dprof registers a `SIGINT` handler
+by default.
+This allows dprof to capture when a process is interrupted by the user,
+and it will write the JSON data and terminate.
+
+If this overriding terminate behavior is undesired, or interferes with an
+existing handler in a program, either a `--dprof-no-sigint` flag can be
+provided to the program, or a `DPROF_NO_SIGINT=1` environment variable.
+
+```
+node -r dprof my-script.js --dprof-no-sigint
+```
+
 ## Format
 
 The `dprof.json.gz` file is a GZIP compressed JSON file. It is possible

dprof.js

@@ -147,7 +147,20 @@ asyncHook.enable();
 // Print result
 //
 
-process.on('exit', function () {
+if (process.argv.indexOf('--dprof-no-sigint') === -1 &&
+    !process.env.hasOwnProperty('DPROF_NO_SIGINT')) {
+  process.on('SIGINT', function handleSIGINT() {
+    writeDataFile();
+
+    // Trigger node's default handler
+    process.removeAllListeners('SIGINT');
+    process.kill(process.pid, 'SIGINT');
+  });
+}
+
+process.on('exit', writeDataFile);
+
+function writeDataFile() {
   // even though zlib is sync, it still fires async_wrap events,
   // so disable asyncWrap just to be sure.
   asyncHook.disable();
@@ -163,4 +176,4 @@ process.on('exit', function () {
   } else {
     fs.writeFileSync('./dprof.json.gz', zlib.gzipSync(JSON.stringify(data)));
   }
-});
+}