Reuse nodejs subprocess for faster expressions (#178)

* Reuse javascript subprocess to reduce script evaluation overhead.

cwltool/cwlNodeEngine.js

@@ -0,0 +1,13 @@
+"use strict";
+process.stdin.setEncoding('utf8');
+var incoming = "";
+process.stdin.on('data', function(chunk) {
+  incoming += chunk;
+  var i = incoming.indexOf("\n");
+  if (i > -1) {
+    var fn = JSON.parse(incoming.substr(0, i));
+    incoming = incoming.substr(i+1);
+    process.stdout.write(JSON.stringify(require("vm").runInNewContext(fn, {})) + "\n");
+  }
+});
+process.stdin.on('end', process.exit);

cwltool/sandboxjs.py

@@ -3,24 +3,36 @@
 import threading
 import errno
 import logging
-from typing import Any, Dict, List, Mapping, Text, TypeVar, Union
+import select
+import os
 
+import cStringIO
+from cStringIO import StringIO
+from typing import Any, Dict, List, Mapping, Text, TypeVar, Union
+from pkg_resources import resource_stream
 
 class JavascriptException(Exception):
     pass
 
 _logger = logging.getLogger("cwltool")
 
-JSON = Union[Dict[Any,Any], List[Any], Text, int, long, float, bool, None]
+JSON = Union[Dict[Text,Any], List[Any], Text, int, long, float, bool, None]
+
+localdata = threading.local()
 
 have_node_slim = False
 
-def execjs(js, jslib, timeout=None):  # type: (Union[Mapping, Text], Any, int) -> JSON
+def new_js_proc():
+    # type: () -> subprocess.Popen
+
+    res = resource_stream(__name__, 'cwlNodeEngine.js')
+    nodecode = res.read()
+
     nodejs = None
     trynodes = ("nodejs", "node")
     for n in trynodes:
         try:
-            nodejs = subprocess.Popen([n], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            nodejs = subprocess.Popen([n, "--eval", nodecode], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
             break
         except OSError as e:
             if e.errno == errno.ENOENT:
@@ -39,7 +51,7 @@ def execjs(js, jslib, timeout=None):  # type: (Union[Mapping, Text], Any, int) -
             nodejs = subprocess.Popen(["docker", "run",
                                        "--attach=STDIN", "--attach=STDOUT", "--attach=STDERR",
                                        "--sig-proxy=true", "--interactive",
-                                       "--rm", nodeimg],
+                                       "--rm", nodeimg, "node", "--eval", nodecode],
                                       stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         except OSError as e:
             if e.errno == errno.ENOENT:
@@ -55,15 +67,24 @@ def execjs(js, jslib, timeout=None):  # type: (Union[Mapping, Text], Any, int) -
             "expressions, but couldn't find it.  Tried %s, docker run "
             "node:slim" % u", ".join(trynodes))
 
+    return nodejs
+
+
+def execjs(js, jslib, timeout=None):  # type: (Union[Mapping, Text], Any, int) -> JSON
+
+    if not hasattr(localdata, "proc") or localdata.proc.poll() is not None:
+        localdata.proc = new_js_proc()
+
+    nodejs = localdata.proc
+
     fn = u"\"use strict\";\n%s\n(function()%s)()" % (jslib, js if isinstance(js, basestring) and len(js) > 1 and js[0] == '{' else ("{return (%s);}" % js))
-    script = u"console.log(JSON.stringify(require(\"vm\").runInNewContext(%s, {})));\n" % json.dumps(fn)
 
     killed = []
 
     def term():
         try:
-            nodejs.kill()
             killed.append(True)
+            nodejs.kill()
         except OSError:
             pass
 
@@ -73,17 +94,44 @@ def term():
     tm = threading.Timer(timeout, term)
     tm.start()
 
-    stdoutdata, stderrdata = nodejs.communicate(script)
+    stdin_buf = StringIO(json.dumps(fn)+"\n")
+    stdout_buf = StringIO()
+    stderr_buf = StringIO()
+
+    completed = []  # type: List[Union[cStringIO.InputType, cStringIO.OutputType]]
+    while len(completed) < 3:
+        rready, wready, _ = select.select([nodejs.stdout, nodejs.stderr], [nodejs.stdin], [])
+        if nodejs.stdin in wready:
+            b = stdin_buf.read(select.PIPE_BUF)
+            if b:
+                os.write(nodejs.stdin.fileno(), b)
+            elif stdin_buf not in completed:
+                completed.append(stdin_buf)
+        for pipes in ((nodejs.stdout, stdout_buf), (nodejs.stderr, stderr_buf)):
+            if pipes[0] in rready:
+                b = os.read(pipes[0].fileno(), select.PIPE_BUF)
+                if b:
+                    pipes[1].write(b)
+                elif pipes[1] not in completed:
+                    completed.append(pipes[1])
+        if stdout_buf.getvalue().endswith("\n"):
+            for buf in (stdout_buf, stderr_buf):
+                if buf not in completed:
+                    completed.append(buf)
     tm.cancel()
 
+    stdin_buf.close()
+    stdoutdata = stdout_buf.getvalue()
+    stderrdata = stderr_buf.getvalue()
+
     def fn_linenum():  # type: () -> Text
         return u"\n".join(u"%04i %s" % (i+1, b) for i, b in enumerate(fn.split("\n")))
 
-    if killed:
-        raise JavascriptException(u"Long-running script killed after %s seconds.\nscript was:\n%s\n" % (timeout, fn_linenum()))
-
-    if nodejs.returncode != 0:
-        raise JavascriptException(u"Returncode was: %s\nscript was:\n%s\nstdout was: '%s'\nstderr was: '%s'\n" % (nodejs.returncode, fn_linenum(), stdoutdata, stderrdata))
+    if nodejs.poll() not in (None, 0):
+        if killed:
+            raise JavascriptException(u"Long-running script killed after %s seconds.\nscript was:\n%s\n" % (timeout, fn_linenum()))
+        else:
+            raise JavascriptException(u"Returncode was: %s\nscript was:\n%s\nstdout was: '%s'\nstderr was: '%s'\n" % (nodejs.returncode, fn_linenum(), stdoutdata, stderrdata))
     else:
         try:
             return json.loads(stdoutdata)

setup.py

@@ -34,7 +34,8 @@
                                 'schemas/v1.0/*.yml',
                                 'schemas/v1.0/*.md',
                                 'schemas/v1.0/salad/schema_salad/metaschema/*.yml',
-                                'schemas/v1.0/salad/schema_salad/metaschema/*.md']},
+                                'schemas/v1.0/salad/schema_salad/metaschema/*.md',
+                                'cwlNodeEngine.js']},
       install_requires=[
           'requests',
           'ruamel.yaml == 0.12.4',