Fix a bug, add some testcases.

[python_utils.git] / bootstrap.py

diff --git a/bootstrap.py b/bootstrap.py
index 35747865b7aacc38fa61f6005af6c5bd5833ff69..50af84407f57e504632e868a1b1e2de32a19a671 100644 (file)
--- a/bootstrap.py
+++ b/bootstrap.py
@@ -1,5 +1,11 @@
 #!/usr/bin/env python3
 
+"""This is a module for wrapping around python programs and doing some
+minor setup and tear down work for them.  With it, you can break into
+pdb on unhandled top level exceptions, profile your code by passing a
+commandline argument in, audit module import events, examine where
+memory is being used in your program, and so on."""
+
 import functools
 import importlib
 import logging
@@ -101,6 +107,15 @@ def handle_uncaught_exception(exc_type, exc_value, exc_tb):
 
 
 class ImportInterceptor(importlib.abc.MetaPathFinder):
+    """An interceptor that always allows module load events but dumps a
+    record into the log and onto stdout when modules are loaded and
+    produces an audit of who imported what at the end of the run.  It
+    can't see any load events that happen before it, though, so move
+    bootstrap up in your __main__'s import list just temporarily to
+    get a good view.
+
+    """
+
     def __init__(self):
         import collect.trie
 
@@ -111,9 +126,9 @@ class ImportInterceptor(importlib.abc.MetaPathFinder):
 
     def repopulate_modules_by_filename(self):
         self.module_by_filename_cache.clear()
-        for mod in sys.modules:
-            if hasattr(sys.modules[mod], '__file__'):
-                fname = getattr(sys.modules[mod], '__file__')
+        for _, mod in sys.modules.copy().items():  # copy here because modules is volatile
+            if hasattr(mod, '__file__'):
+                fname = getattr(mod, '__file__')
             else:
                 fname = 'unknown'
             self.module_by_filename_cache[fname] = mod
@@ -243,8 +258,7 @@ def initialize(entry_point):
 
         # Maybe log some info about the python interpreter itself.
         logger.debug(
-            'Platform: %s, maxint=0x%x, byteorder=%s',
-            sys.platform, sys.maxsize, sys.byteorder
+            'Platform: %s, maxint=0x%x, byteorder=%s', sys.platform, sys.maxsize, sys.byteorder
         )
         logger.debug('Python interpreter version: %s', sys.version)
         logger.debug('Python implementation: %s', sys.implementation)
@@ -320,7 +334,12 @@ def initialize(entry_point):
             'child system: %.4fs\n'
             'machine uptime: %.4fs\n'
             'walltime: %.4fs',
-            utime, stime, cutime, cstime, elapsed_time, walltime
+            utime,
+            stime,
+            cutime,
+            cstime,
+            elapsed_time,
+            walltime,
         )
 
         # If it doesn't return cleanly, call attention to the return value.