Dear Maintainer,

Currently, tkcvs is not working for me.
Instead, the tkcvs window shows, but then it hangs, with 'wish' taking 100%
cpu.

I have this issue with multiple repos, and commandline cvs works fine.
Also under fedora I have used tkcvs without problems before.

Is there a way to further debug this?

strace tkcvs spits out messages like:

poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3,
revents=POLLIN|POLLOUT}])
recvmsg(3, {msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\6\0~6\210\356R\n\325\0\0\0\251\0\0\4\0\0\0\0\232\10.\4\30\4\f\0\0\0\1\0"...,
iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 4096
writev(3,
[{iov_base="-\303\5\0\273\223\2\4\5\0\2\0fixed\303\5\0007\221\5\0\274\223\2\4\302\1\0\4"...,
iov_len=16380}, {iov_base="fixed", iov_len=5}, {iov_base="\0\0\0", iov_len=3}],
3) = 16388
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3,
revents=POLLIN|POLLOUT}])
recvmsg(3, {msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\f\0~6\323\1\0\4\0\0\0\0\311\0\23\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 4096
writev(3,
[{iov_base="7\303\5\0\352\225\2\4\302\1\0\4\0@\0\0\351\225\2\0047\221\6\0\353\225\2\4\302\1\0\4"...,
iov_len=16384}, {iov_base=NULL, iov_len=0}, {iov_base="", iov_len=0}], 3) =
16384
recvmsg(3, {msg_name=NULL, msg_namelen=0,
msg_iov=[{iov_base="\6\0\333:\230\362R\n\325\0\0\0\314\0\0\4\0\0\0\0\263\10<\4\36\0\v\0\0\0\1\0"...,
iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 1056
recvmsg(3, {msg_namelen=0}, 0)          = -1 EAGAIN (Resource temporarily
unavailable)
brk(0x5584eb7fb000)                     = 0x5584eb7fb000



Note, similar to bug 519983, which is rather uninformative.

A fix is to have tkcvs use wish 8.5 instead of 8.6.
Edit /usr/bin/tkcvs to read

exec wish8.5 "$0" -- ${1+"$@"}

Launchpad has this one-liner bugfix / workaround, but so far has not been applied.

https://bugs.launchpad.net/ubuntu/+source/tkcvs/+bug/1817571/comments/1

This works for TkCVS 8.2.3

Later releases of TkCVS, or TkRev as it's now called, do not have this code
anymore.