HeaderDebugPanel sometimes triggers an exception for no response.

[jvanasco]

The issue appears to happen when I raise a pyramid.httpexceptions redirect early during a class-based view handler. (in __init__, not call() ). I haven't been able to pinpoint exactly why this happens (version 4.5). The stacktrace below.

I tweaked the debugtoolbar class to handle not having a response and can easily submit a PR for it - but this doesn't make much sense to me and I wonder if this is an issue with Pyramid's handling.

	2018-12-04 14:01:30,295 ERROR [waitress][waitress] Exception when serving /
	Traceback (most recent call last):
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/waitress/channel.py", line 338, in service
		task.service()
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/waitress/task.py", line 169, in service
		self.execute()
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/waitress/task.py", line 399, in execute
		app_iter = self.channel.server.application(env, start_response)
	  File "/Users/jvanasco/webserver/sites/MyApp/trunk/python-packages/myapp/myapp/pyramid_utils/request.py", line 32, in __call__
		return self.application(environ, start_response)
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid/router.py", line 270, in __call__
		response = self.execution_policy(environ, self)
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid/router.py", line 279, in default_execution_policy
		return request.invoke_exception_view(reraise=True)
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid/view.py", line 768, in invoke_exception_view
		reraise_(*exc_info)
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid/router.py", line 277, in default_execution_policy
		return router.invoke_request(request)
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid/router.py", line 260, in invoke_request
		request._process_finished_callbacks()
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid/request.py", line 138, in _process_finished_callbacks
		callback(self)
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid_debugtoolbar/panels/headers.py", line 19, in finished_callback
		self.process_response_deferred()
	  File "/Users/jvanasco/webserver/environments/legacy-2.7.13/lib/python2.7/site-packages/pyramid_debugtoolbar/panels/headers.py", line 31, in process_response_deferred
		response = self.response
	AttributeError: 'HeaderDebugPanel' object has no attribute 'response'

[mmerickel]

if you can reproduce this issue then the question is which codepath the request went through the tween in which self.process_response was not invoked. I'd put a breakpoint around [1] and step through until the response goes out.

[1]

pyramid_debugtoolbar/src/pyramid_debugtoolbar/toolbar.py

Line 246 in af65e64

request.pdtb_id = hexlify(id(request))

First of all, thanks for a great toolbar, it's been very useful.

I've been seeing this error occasionally as well. I just put a breakpoint at the place suggested by mmerickel above and got some more info: in my case the exception got triggered in https://github.com/Pylons/pyramid_debugtoolbar/blob/4.5/src/pyramid_debugtoolbar/toolbar.py#L75 . The panel_class(request) call failed due to an exception raised in panel_class.__init__().

In my case it turned out to be a UnicodeDecodeError exception in a custom panel's __init__(). Fixing this exception also fixed the issue with HeaderDebugPanel.

Note: the faulty custom panel's class was (way) after the HeaderDebugPanel class in the panel_classes list, so this part of the code should've already ran for HeaderDebugPanel, making me guess it's to do with some later code that doesn't run due to the raised exception. I didn't investigate any further.

Using Pyramid Debugtoolbar 4.5.