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Re: Problem reports for version control systems

On 2021-05-01 23:54, Brett Lymn wrote:
On Sat, May 01, 2021 at 12:58:50PM +1200, Lloyd Parkes wrote:

Germany is pretty much the opposite of New Zealand. It's close to
everywhere, but its last mile access speeds are a bit infamous.

Just for you info... there are a few NetBSD developers in .au, my self included.  I haven't
had any issues with cvs disconnects.  Not to deny you have an issue, just letting you know
it works ok for people near you.

Not anywhere near such a location, but just adding that cvs works fine for me too, but yes, there is a lot of disk activity on the local machine before anything even starts downloading, and a lot of activity at the end where it updates file metadata as well as clean out empty directories (if you added pruning).

I'm running some tests on other local clients and against other CVS mirrors
in the hope that come up with a better characterisation of the problem than
"it doesn't work".

If you have the space, a tcpdump from both sides of your firewall may provide a clue.

I suspect what is commonly the problem here is related to the fact that cvs has such a phase at the beginning where it is scanning through the file system, which can take quite a while. Some NAT devices along the path sometimes have timeouts on existing connections that if no traffic is happening for a while, they are dropped, even though there hasn't been any FINs on the connection. So a connection that just don't have any traffic for a while are hit by this, which is exactly the pattern you have with cvs.

I've seen the same effect on a simple telnet session, where ssh survives fine. And there it's just that when the connection is idle, telnet is not creating any traffic at all, while ssh do generate a bit of traffic even if there is no activity.

So one obvious solution is to use something like ssh as a carries for the cvs traffic, if possible, or else see if some kind of keepalives can be enabled on a connection, to defeat NAT and similar devices which aggressively drop connections on which there is no traffic for a while. (Or, of course, if there is a NAT you have control over, you might be able to change how it behaves...)


Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email:             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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