Hi,

Seeing sftp download issue after updating from 7.44.0 to 7.49.1
(patched with: https://curl.haxx.se/mail/lib-2016-06/0139.html).
Application code is exactly the same. 

Downloading via sftp sees significant decrease in speed and eventually
stalls without any indication of error or timeout. Download never
resumes following the stall.

The same result occurs using the curl command line tool.

With 7.44.0 average sftp download speed is ~3MBs/sec. With 7.49.1 speed
registers initially at ~100KB/sec and slowly increments to ~600KB/sec.
With large files (256MB) the download stalls and does not recover. No
SSH disconnects or errors are seen on the server (until my abort
logic).

Application uses libcurl's internal fwrite for transfers.

Uploads works as expected in both versions.

Debug output from 7.44 and 7.49 show no obvious differences. Receives
just cease to occur. Setting the FTP_RESPONSE_TIMEOUT option to 10
seconds (< progress timeout logic) does not cause a timeout.

Here are the setopts performed for download:

CURLOPT_FTP_RESPONSE_TIMEOUT (10)
CURLOPT_INTERFACE
CURLOPT_URL
CURLOPT_NOPROGRESS (0)
CURLOPT_XFERINFOFUNCTION
CURLOPT_CONNECTTIMEOUT (30)
CURLOPT_MAX_RECV_SPEED_LARGE (0)
CURLOPT_WRITEDATA
CURLOPT_MAXFILESIZE
CURLOPT_DEBUGFUNCTION/VERBOSE (tried enabled/disabled)

Build options: zlib, libssh2, crypto, debug, disable ldap/ldaps,
without libidn

Regards,
Dan Donahue

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Received on 2016-07-20