fix bug where npm calls ran CPU at 100% - fixes issue #16

pixiedust_node/nodestdreader.py

@@ -1,6 +1,7 @@
 from pixiedust.display import *
 from pixiedust.utils.shellAccess import ShellAccess
 from threading import Thread
+from threading import Event
 import IPython
 import json
 import pandas
@@ -17,14 +18,18 @@ class NodeStdReader(Thread):
 
     def __init__(self, ps):
         super(NodeStdReader, self).__init__() 
+        self._stop_event = Event()
         self.ps = ps
         self.daemon = True
         self.start()
 
+    def stop(self):
+        self._stop_event.set()
+
     def run(self):
-        
+
         # forever
-        while(True):
+        while(self._stop_event.is_set() == False):
             # read line from Node's stdout
             line = self.ps.stdout.readline()
 
@@ -61,4 +66,4 @@ def run(self):
 
             except Exception as e:
                 print(line)
-                print(e)
+                print(e)

pixiedust_node/npm.py

@@ -30,8 +30,13 @@ def cmd(self, command, module):
 
         # create thread to read this process's output          
         t = NodeStdReader(ps)
+
+        # wait for the sub-process to exit
         ps.wait()
 
+        # tell the thread reading its output to stop too, to prevent 100% CPU usage
+        t.stop()
+
     def install(self, module):
         self.cmd('install', module)
 

pixiedust_node/package.json

@@ -1,6 +1,6 @@
 {
   "name": "pixiedust_node",
-  "version": "0.1.5",
+  "version": "0.1.6",
   "description": "Run Node.js cells in Jupyter notebooks with Pixiedust",
   "main": "pixiedustNodeRepl.js",
   "scripts": {

setup.py

@@ -1,7 +1,7 @@
 from setuptools import setup, find_packages
 
 setup(name='pixiedust_node',
-      version='0.1.5',
+      version='0.1.6',
       description='Pixiedust extension for Node.js',
       url='https://github.com/ibm-watson-data-lab/pixiedust_node',
       install_requires=['pixiedust'],