Re: Tomcat 9.0.52 http2 flow control issues

[Mark Thomas <ma...@apache.org>]

On 20/09/2021 07:28, Mark Thomas wrote:
> On 10/09/2021 11:42, Mark Thomas wrote:
>> Hi Erik,
>>
>> Thanks for the report. I'm looking at this now.
>>
>> I'm testing with a simple index page that references 3 largish images 
>> (~6MB each).
>>
>> I've found an issue with HTTP/2, sendfile and StackOverflowExcpetion 
>> that I have a local fix for.
>>
>> With that fix in place, I can see a flow control issue. Somehow, a 
>> stream is getting a larger allocation from the connection control 
>> window than the stream control window. That leads to some internal 
>> values having unexpected (negative) values and things quickly escalate 
>> to the connection closing abruptly from there. I'm currently looking 
>> into how this happens.
>>
>> I'm not sure if I am seeing a different issue to you or just a 
>> different symptom of the same issue. I'll keep the thread updated with 
>> progress.
> 
> I found the root cause - there were further concurrency issues in the 
> connection flow control window management. I've refactored the code to 
> simplify the approach and (hopefully) make it more robust. I am no 
> longer able to recreate the issue I was seeing.
> 
> The fixes will be in the October release round. If anyone would like to 
> test this sooner than that, you can build from source or I can make a 
> test build available on request.

The 9.0.54 release vote is in progress. If you'd like to test this, 
details of where to get the files are on 9.0.54 VOTE thread on the dev 
list. (Note: Only if the VOTE passes is this an official release. Until 
then it is made available for testing purposes only). There will be 
announcement on this list if the VOTE passes and the release becomes 
official. If all goes well, that should be early next week.

Mark


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