debug: On SIGUSR2, we dump tracebacks for all threads to screen

mitmproxy/main.py

@@ -47,7 +47,7 @@ def process_options(parser, options):
         sys.exit(0)
     if options.quiet:
         options.verbose = 0
-    debug.register_info_dumper()
+    debug.register_info_dumpers()
     return config.process_proxy_options(parser, options)
 
 

netlib/debug.py

@@ -4,6 +4,7 @@ import sys
 import threading
 import signal
 import platform
+import traceback
 
 import psutil
 
@@ -76,5 +77,18 @@ def dump_info(sig, frm, file=sys.stdout):  # pragma: no cover
     print("****************************************************", file=file)
 
 
-def register_info_dumper():  # pragma: no cover
+def dump_stacks(signal, frame, file=sys.stdout):
+    id2name = dict([(th.ident, th.name) for th in threading.enumerate()])
+    code = []
+    for threadId, stack in sys._current_frames().items():
+        code.append("\n# Thread: %s(%d)" % (id2name.get(threadId,""), threadId))
+        for filename, lineno, name, line in traceback.extract_stack(stack):
+            code.append('File: "%s", line %d, in %s' % (filename, lineno, name))
+            if line:
+                code.append("  %s" % (line.strip()))
+    print("\n".join(code), file=file)
+
+
+def register_info_dumpers():  # pragma: no cover
     signal.signal(signal.SIGUSR1, dump_info)
+    signal.signal(signal.SIGUSR2, dump_stacks)

test/netlib/test_debug.py

@@ -10,5 +10,11 @@ def test_dump_info():
     assert cs.getvalue()
 
 
+def test_dump_stacks():
+    cs = StringIO()
+    debug.dump_stacks(None, None, file=cs)
+    assert cs.getvalue()
+
+
 def test_sysinfo():
     assert debug.sysinfo()