Preferred bug tracker

Please visit the preferred bug tracker to report your issue.

This queue is for tickets about the Net-SSH2 CPAN distribution.

Report information
The Basics
Id:
18939
Status:
resolved
Priority:
Low/Low
Queue:

People
Owner:
Nobody in particular
Requestors:
stephenclouse@gmail.com(no email address set)
Cc:
AdminCc:

BugTracker
Severity:
Important
Broken in:
0.05
Fixed in:
(no value)



Subject: Net::SSH2::Channel objects not getting destroyed
Bug report for Net::SSH2 0.07 running under perl 5.8.6 (Fedora Core 4) I am using Net::SSH2 as part of a persistent daemon. My issue is that ::Channel objects (including those that are implicitly created by scp_get) are not getting destroyed, even though they are leaving scope. This prevents the main Net::SSH2 object from getting destroyed when it goes out of scope, which causes both a memory leak and a socket descriptor leak. After a few hours of running, our process fd space looks like this: total 284 lrwx------ 1 64 Apr 7 13:43 0 -> /dev/pts/2 lrwx------ 1 64 Apr 7 13:43 1 -> /dev/pts/2 lrwx------ 1 64 Apr 7 13:43 10 -> socket:[23023727] lrwx------ 1 64 Apr 7 13:43 100 -> socket:[25941479] lrwx------ 1 64 Apr 7 13:43 101 -> socket:[25942954] lrwx------ 1 64 Apr 7 13:43 102 -> socket:[25943607] lrwx------ 1 64 Apr 7 13:43 103 -> socket:[25945043] lrwx------ 1 64 Apr 7 13:43 104 -> socket:[25945575] lrwx------ 1 64 Apr 7 13:43 105 -> socket:[25946014] lrwx------ 1 64 Apr 7 13:43 106 -> socket:[25947262] lrwx------ 1 64 Apr 7 13:43 107 -> socket:[25947851] lrwx------ 1 64 Apr 7 13:43 108 -> socket:[25949223] lrwx------ 1 64 Apr 7 13:43 109 -> socket:[25950742] lrwx------ 1 64 Apr 7 13:43 11 -> socket:[23024789] lrwx------ 1 64 Apr 7 13:43 110 -> socket:[25951710] lrwx------ 1 64 Apr 7 13:43 111 -> socket:[25952922] lrwx------ 1 64 Apr 7 13:43 112 -> socket:[25953707] lrwx------ 1 64 Apr 7 13:43 113 -> socket:[25955436] lrwx------ 1 64 Apr 7 13:43 114 -> socket:[25957008] lrwx------ 1 64 Apr 7 13:43 115 -> socket:[25957766] lrwx------ 1 64 Apr 7 13:43 116 -> socket:[25958984] lrwx------ 1 64 Apr 7 13:43 117 -> socket:[25993099] ...and so on. Eventually the process either consumes all memory or hits the system fd limit and aborts. Here is some debug output from two different sessions. The first one is looking for files to copy (using SFTP stat) but doesn't find any. At the end the Net::SSH2 object is destroyed. [debug] start ssh session libssh2_sftp_init(ss->session) -> 0xa7cc6c0 hv_from_attrs: attrs->flags = 15 hv_from_attrs: attrs->flags = 15 libssh2_sftp_open_ex(sf->sftp, (char*)pv_file, len_file, l_flags, mode, 0) -> 0x0 libssh2_sftp_open_ex(sf->sftp, (char*)pv_file, len_file, l_flags, mode, 0) -> 0x0 libssh2_sftp_open_ex(sf->sftp, (char*)pv_file, len_file, l_flags, mode, 0) -> 0x0 libssh2_sftp_open_ex(sf->sftp, (char*)pv_file, len_file, l_flags, mode, 0) -> 0x0 Net::SSH2::SFTP::DESTROY Net::SSH2::SFTP::DESTROY freeing session Net::SSH2::DESTROY [debug] end ssh session The second session does find files it needs to pull down, and calls scp_get to copy them. Notice the destructor is NOT getting called at the end. [debug] start ssh session libssh2_sftp_init(ss->session) -> 0xab1d610 libssh2_sftp_open_ex(sf->sftp, (char*)pv_file, len_file, l_flags, mode, 0) -> 0xa7cdc88 libssh2_scp_recv(ss->session, path, &st) -> 0xcc0aa88 Net::SSH2::Channel::read(size = 1736739, ext = 0) - read 1736739 total Net::SSH2::Channel::read(size = 1, ext = 0) - read 1 bytes - read 1 total libssh2_sftp_open_ex(sf->sftp, (char*)pv_file, len_file, l_flags, mode, 0) -> 0xc403f38 libssh2_scp_recv(ss->session, path, &st) -> 0xb50bae8 Net::SSH2::Channel::read(size = 826046, ext = 0) - read 826046 total Net::SSH2::Channel::read(size = 1, ext = 0) - read 1 bytes - read 1 total libssh2_sftp_open_ex(sf->sftp, (char*)pv_file, len_file, l_flags, mode, 0) -> 0xa7d2b60 libssh2_scp_recv(ss->session, path, &st) -> 0xafb63c8 Net::SSH2::Channel::read(size = 28231, ext = 0) - read 28231 total Net::SSH2::Channel::read(size = 1, ext = 0) - read 1 bytes - read 1 total [debug] end ssh session We have another process similar to this one that opens a shell channel, which suffers from the same problem. Even when the channel object goes out of scope in our program, its destructor is not called, and so the Net::SSH2 object is not destroyed either. The test script itself exhibits this same behavior, if the full interactive test is run. DESTROY is never called. I have tried debugging this myself to no avail. I cannot find where the refcounts are getting erroneously incremented. I also sent an email on this issue to the ssh-sftp-users-list on 4/7 but never received a reply. I'm hoping this is a better way to get someone's attention.


This service runs on Request Tracker, is sponsored by The Perl Foundation, and maintained by Best Practical Solutions.

Please report any issues with rt.cpan.org to rt-cpan-admin@bestpractical.com.