GitHub user realpdm opened an issue:
https://github.com/apache/trafficserver/issues/1478
sscl is occasionally zero (formerly TS-2998)
Scott Beardsley originally reported in
https://issues.apache.org/jira/browse/TS-2998
Running ATS 5.0 it looks like sscl in the extended2.log is occasionally
zero even for cache misses and HTTP 200 reponses... Here is how I am finding
these cases:
```
tail -f extended2.log|awk '$23~/TCP_MISS/&&$11~/200/&&$12~/^0/
print $10,$11,$12,$23,$7
21452 200 0 TCP_MISS http://search.example.com/search?p=pizza
```
You can see that pscl ($10) is non-zero but sscl ($12) is zero. Where is
ats getting the content from if it isn't coming from the origin? Is this
related to the value of the content-length header from the origin? Ideally we
would want to see the raw number of bytes coming from the origin.
Then Sudheer Vinukonda suggested:
> Now that I think of it, this may be related to TS-3049. Scott, do you
know if you are seeing this issue only for a spdy client connection or do you
also see this for non-spdy clients? Now that we have the fix for TS-3049
available, it might also be interesting to see if the issue still occurs after
the fix is deployed.
And Scott responded
I just tried 5.0.1_20 (Y! version) and this specific problem persists...
I'm reasonably certain this is unrelated to SPDY because I see it on machines
which only serve HTTP traffic.
There could be some content-length/chunked issue going on, not sure. I do
see this across a few drastically different origins.
The rate at which it happens is as follows:
HTTPS-only traffic: 24.9%
HTTP-only traffic: 25.6%
I haven't been able to isolate it yet. I'll start disabling plugins to see
if the problem is some strange interaction with my setup.
And Karthik added:
I'm using 4.2.x and I see that sscl is always 0 when gzip is enabled. When
I disable gzipping of response, sscl is set correctly.
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