Curl upgrade from 7.65.1 to 7.70.0 causing performance degradation

Hello All,

This is continuation of an earlier thread
<https://curl.haxx.se/mail/archive-2020-09/0016.html>, that was addressed
to an incorrect audience. Using curl-library mailing for further discussion.

I further investigated the issue. As I mentioned earlier, we use the
connection pause/unpause feature. If the connection is paused then the
library uses a temporary buffer (pausewrite function
<https://github.com/curl/curl/search?q=pausewrite&unscoped_q=pausewrite>)
for holding the data. I noticed that this buffer continues to increase
(buffer size reaches upto 7mb for 13mb response) and malloc, memcpy calls
on the buffer of this size causes slowness. Further investigation revealed
that buffer size increase has been taking place since the following change
<https://github.com/curl/curl/commit/e040146f22608fd92c44be2447a6505141a8a867>
was
introduced in the library. Before this change, we did not notice any
performance degradation. I compared buffer size before and after the
change, screenshot attached here. How do you think we can proceed from here
for fixing this issue?

https://github.com/curl/curl/commit/e040146f22608fd92c44be2447a6505141a8a867

Thanks for taking time to read this query.
[image: image.png]

Best,
Kunal

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