WIP: Independent child process monitoring #118

.gitignore

@@ -5,3 +5,6 @@ MANIFEST
 *.egg-info
 *.pyc
 *~
+
+# Ignore mprof generated files
+mprofile_*.dat

examples/multiprocessing_example.py

@@ -0,0 +1,55 @@
+"""
+An undecorated example of a script that allocates memory in multiprocessing
+workers to demonstrate the use of memory_profiler with multiple processes.
+
+Run this script with mprof run -C python multiprocessing_example.py
+You can then visualize the usage with mprof plot.
+"""
+
+import time
+import multiprocessing as mp
+
+# Big numbers
+X6 = 10 ** 6
+X7 = 10 ** 7
+
+
+def worker(num, wait, amt=X6):
+    """
+    A function that allocates memory over time.
+    """
+    frame = []
+
+    for idx in range(num):
+        frame.extend([1] * amt)
+        time.sleep(wait)
+
+    del frame
+
+
+def main_sequential():
+    """
+    A sequential version of the work, where one worker is called at a time.
+    """
+    worker(5, 5, X6)
+    worker(5, 2, X7)
+    worker(5, 5, X6)
+    worker(5, 2, X7)
+
+
+def main_multiproc():
+    """
+    A multiprocessing version of the work, where workers work in their own
+    child processes and are collected by the master process.
+    """
+    pool    = mp.Pool(processes=4)
+    tasks   = [
+        pool.apply_async(worker, args) for args in
+        [(5, 5, X6), (5, 2, X7), (5, 5, X6), (5, 2, X7)]
+    ]
+
+    results = [p.get() for p in tasks]
+
+
+if __name__ == '__main__':
+    main_multiproc()

memory_profiler.py

@@ -86,6 +86,38 @@ def _repr_pretty_(self, p, cycle):
         p.text(u'<MemitResult : ' + msg + u'>')
 
 
+def _get_child_memory(process, meminfo_attr=None):
+    """
+    Returns a generator that yields memory for all child processes.
+    """
+    if not has_psutil:
+        raise NotImplementedError((
+            "The psutil module is required to monitor the "
+            "memory usage of child processes."
+        ))
+
+    # Convert a pid to a process
+    if isinstance(process, int):
+        if process == -1: process = os.getpid()
+        process = psutil.Process(process)
+
+    if not meminfo_attr:
+        # Use the psutil 2.0 attr if the older version isn't passed in.
+        meminfo_attr = 'memory_info' if hasattr(process, 'memory_info') else 'get_memory_info'
+
+    # Select the psutil function get the children similar to how we selected
+    # the memory_info attr (a change from excepting the AttributeError).
+    children_attr = 'children' if hasattr(process, 'children') else 'get_children'
+
+    # Loop over the child processes and yield their memory
+    try:
+        for child in getattr(process, children_attr)(recursive=True):
+            yield getattr(child, meminfo_attr)()[0] / _TWO_20
+    except psutil.NoSuchProcess:
+        # https://github.com/fabianp/memory_profiler/issues/71
+        yield 0.0
+
+
 def _get_memory(pid, backend, timestamps=False, include_children=False, filename=None):
     # .. low function to get memory consumption ..
     if pid == -1:
@@ -111,12 +143,7 @@ def ps_util_tool():
                 else 'get_memory_info'
             mem = getattr(process, meminfo_attr)()[0] / _TWO_20
             if include_children:
-                try:
-                    for p in process.children(recursive=True):
-                        mem += getattr(p, meminfo_attr)()[0] / _TWO_20
-                except psutil.NoSuchProcess:
-                    # https://github.com/fabianp/memory_profiler/issues/71
-                    pass
+                mem +=  sum(_get_child_memory(process, meminfo_attr))
             if timestamps:
                 return mem, time.time()
             else:
@@ -128,9 +155,11 @@ def ps_util_tool():
     def posix_tool():
         # .. scary stuff ..
         if include_children:
-            raise NotImplementedError('The psutil module is required when to'
-                                      ' monitor memory usage of children'
-                                      ' processes')
+            raise NotImplementedError((
+                "The psutil module is required to monitor the "
+                "memory usage of child processes."
+            ))
+
         warnings.warn("psutil module not found. memory_profiler will be slow")
         # ..
         # .. memory usage in MiB ..