On Thu, 31 May 2001, Venugopal R. Neerudu wrote:
> I am using Polygraph 2.5.4 and I am getting a client side error
> message which says "Polygraph hit an uncachable object". I am
> also using command line option --dump err. However, in order to
> debug the cache, how do I get more information regarding the error
> message. I would like to know through additional information, if
> this can be reproduced again so that it would be easy for
> debugging purposes.
The information you get with "--dump err" is probably almost
everything Polygraph knows about the error at the time the error
message is dumped.
To get more information, you can use "--dump hdrs,errs" option that
will print all request and response headers in addition to the error
headers. You can then match the error response with the request that
caused an error. You can do that on both client and server side to get
even more information.
The most common cause of the above error is the proxy making a
decision to merge two responses before the proxy sees the response
headers that indicate that the content is not cachable. In other
words, when some proxies receive two ~simultaneous requests for the
same URL, they generate only one response regardless of object
cachability. This is, of course, wrong and Polygraph complains about
There could be other reasons, of course.
P.S. Polygraph 2.6 will enable/disable "--dump hdrs" run-time when
sent a USR1 signal. This is handy if you do not want to dump
all headers from the very beginning of the test.
This archive was generated by hypermail 2b29 : Tue Jul 10 2001 - 12:00:19 MDT