[SOLVED] Odd hangs with Synergy

[megosdog]

Okay, I'm looking for ideas on how to fix an odd hangup issue with Synergy KVM. I'm running two machines, one's a laptop, the other a desktop. The desktop is server, the laptop is client. Everything is hard wired on gig cat6 ether. Laptop is where I'm seeing the pauses and hangs with keyboard and mouse reactions. And it seems like every either 20 or 30 seconds the keyboard and mouse just freeze when using them via Synergy. If I use them via the laptop's own keyboard and the mouse directly connected to the machine, there's no hang. Just when they're controlled by Synergy. The hang typically lasts 5-10 seconds, then anything I was doing during the hangup, be that typing, scrolling, etc, all suddenly unloads on the laptop sorta like it got backed up and then suddenly caught up again. There's no actual issues with the network connection, data continues flowing, downloads do their thing, streams continue to work, etc, etc.

The only thing hanging up is Synergy, and only on the laptop (client), but not the main PC (server). There's no errors being generated in Synergy, SSL is not enabled, and there's no load on either device when these hangups happen. They happen with a surprising regularity and almost what I would call a predictable cycle with predictable timing. So yeah, I've troubleshooted everything I can think of. If you guys have some ideas on how to debug what's going on with this, I'm all ears. Also, the Laptop is a Toshiba, desktop is a Lenovo.

[oshunluvr]

I assume you've set logging to Debug 2 on both the client and server? Synergy is very verbose at that level so you should see a hint. Honestly if Synergy isn't logging anything suspicious, I'd look into your network connection instead. I've had a few oddities using Synergy lately, but my client is Windows 10 so I blame it on that.

Have you tried asking Symless? They've been responsive to me in the past. Also you didn't say what version you're using. I'm still using 1.10.1 but 1.11.1 is the latest, or you could try the beta version 2.

[megosdog]

I have 1.8.8 currently installed. Let me bump the logging up to level 2 and see what it says.

EDIT: Oh this is interesting. I have Synergy Pro free edition, but they're evidently not offering that anymore. Well, that sucks. Also, it's on debug level 2 and it's not generating any logs. Still gonna let this run for a bit, but that's super odd.

EDIT2: Interesting, it's reporting itself as a FOSS project, yet they make you buy it. Um, okay...

[megosdog]

Okay, that was interesting. Pushed it to debug level 2 and it logged so much stuff it crashed my workstation. o.0 No errors in the logs though. Just lots of mouse movement notifications and entering and leaving the screen.

[oshunluvr]

AFAIK, it started as a FOSS program but went commercial eventually. There's a license on the website. I bought a lifetime PRO license when they first went to the pay scheme. I love the program - it's a really simple solution to an annoying problem - that being having 2 or more keyboard/mouse sets on my desk. I have noticed lately it take awhile for my client to connect, but being Windows 10 I assume that's the problem.

If no errors, then maybe the problem isn't being caused by Synergy. Are you using the default port? I switch from the default. Maybe there's a port conflict? Jut really guessing at this point.

[megosdog]

I'm using port 24800. Not sure if that's default or not. o.0 I also got deeper into the settings and found that "synchronize screensavers" was turned on. Since I use autolock rather than screensavers, I'm wondering if that might be it. I might also try swapping ports later to see if that changes anything.

[megosdog]

[2020-03-27T17:01:21] WARNING: failed to connect to server: server is not responding
/build/synergy-3N7yN5/synergy-1.8.8-stable+dfsg.1/src/lib/synergy/ClientApp.cpp,312

[2020-03-27T17:01:14] WARNING: can't leave screen
/build/synergy-3N7yN5/synergy-1.8.8-stable+dfsg.1/src/lib/server/Server.cpp,491

Well, I have something finally. I'll have to kick this to the Synergy guys and see what they can do with it. Looks like the two sides are complaining, but I'm still not sure who's fault it is.

[sithlord48]

I stopped using synergy a while ago and moved to barrier (fork of Synergy 1.9). I had a similar problem where my client would drop randomly or get really really laggy. Ended up being a firmware issue with the usb controller. See my laptop is to thin to have a network port , so it came with this usb C Adapter instead. All my other net stuff seamed to work correctly while using it, other then barrier that would have either random lag at time or just drop the client. (IT also did the same thing in windows on the same machine)I thought the USB c device was acting up so i tried another of my USB Network Adapter that i have with no change, then one day My Network Manager started to hang if i had a USB NIC in use sometimes (once or twice a week then it became daily or several times a day). While I am not saying this is your issue but if you have a dell laptop with usb C network adapter check your firmware is up to date. Since i updated my firmware last week it has not happened once.

[megosdog]

Ah, interesting. Yeah, I saw that Barrier was a good alternative, but I didn't see any install packages for Kubuntu 18.04. SO I didn't try it yet. Do you know if that's in the repos, and if not, where to find it so I can install it?

[sithlord48]

This ppa has packages for Bionic ppa https://launchpad.net/~jonathonf/+ar...ubuntu/barrier

[megosdog]

BTW, I think I might've figured out what could be causing this. My laptop has that horrible RealTek chipset. I remember when I first setup the laptop all the pain and suffering I had just getting that working right. So I'm betting that's 90% of my issue. But, I'll take your PPA and see if I can get Barrier installed and working and see if that fixes the issue.

[megosdog]

I finally got a chance to install Barrier. OMG what a difference! The lag I was seeing in my PC is gone, there's literally no hangup between the two machines, no slowdown, no hangs, none of that. It's just pure Pc to laptop mouse/keyboard bliss. Makes me wish I'd have made this change sooner.

[megosdog]

Okay, interesting observations, and I think this part isn't either network, nor Barrier, but rather the laptop. With Synergy, when one would die, both would. With Barrier it's one or the other, but rarely both, and it's more like a stutter pause than a 15 second lockup, and it seems to happen in high load situations. So I think I've somewhat narrowed down more of the reasons the weird hangups were happening. But either way, Barrier is really helping a lot. Anyhow, I'm gonna mark this solved as I don't think it's the KVM software anymore with me moving to Barrier. I think the rest is just performance issues, and the infamous AMD stutter, I need to sort out.

[sithlord48]

Great to hear Barrier is working well for you.

[megosdog]

Okay, after 6 weeks of getting my butt handed to me with work I finally got back to this. Via a tip from a fellow coworker, I fired up tcpdump. It showed me that there is a gobton of inbound and outbound traffic when the mouse is running. There's even a ton when the slave system (my laptop) hangs and the mouse/keyboard stop working for a time. So, what that tells me is there's LOTS of network activity that the kernel is seeing, meaning there's no network issue that I can find as what's happening on the host is also happening on the guest in lock step synchronicity. So, I decided to dig into the logs in barrier and I noticed that there were a number of "disconnected from server" notices. And, mind you, this is with Barrier, not Synergy. With Synergy it was WAY worse. So my thoughts are that there's something else at play here. And I know it's not the network as tcpdump on both machines showed that that was working without issue and with great speed.

The only commonality to all situations is the laptop, which is presently the slave system. So I'm wondering if you guys have any ideas on how I can further troubleshoot this. I'm really scratching my head here.

As a note of observation, load on the laptop, while the hangs happen, is super low, so it's not a load issue. It runs a 4 core AMD A4 with 8gb of memory, so plenty of resources. Plus the HDD is an SSD, so speed there is no issue. Again, whenever the laptop is operating on its own keyboard and mouse there's no performance issues. Only when I go and try to control it with barrier. And there's no real pattern to when the hangs happen, although I have seen them to be most common with times when I'm doing drag and drop, be it a file, a browser tab, text, etc. Now, that's not EVERY hang, but that seems to be the best way to trigger the hangs if I'm testing. Anyhow, ideas welcome. And, if you don't have any, do you know someone or some group who might be better to talk to?