Too many writes to wake-up pipe?

Submitted by caseyboardman on #1

I am testing client version 4.2.3 on Debian, and eventually I end up seeing this in the system log:

"VirtualHere Client: assert:../src/unix/wakeuppipe.cpp,102,OnReadWaiting,size == 1,Too many writes to wake-up pipe?"

Once I see that, I can no longer communicate with the service. I don't see anything else in the logs before that indicate something untoward is going on.

Background:
- I am communicating with the service from my code by writing/reading to/from the pipes directly. (We've been doing this for a while and it seems pretty stable with version 3.8.9)
- The VMs these tests run on get rebooted pretty often, and given that a reboot seems to fix it, it's been a pain to recreate (I'm trying).

Any specific things to look for is appreciated. Additionally, I'd like to request a "-verbose" option so we can run the service and get as much data as possible in the logs to help track down the occasional-but-fairly-consistent errors.

Thanks!

Submitted by Michael on Thu, 2017/09/21 - 12:00

#2

Hi Casey, i just got another report of this a few days ago for another customer so im looking into it now...

Are you just writing to pipe, then waiting for a read to return then repeating the process? You do not have multiple read/writes to the same client at the same time, as the IPC is not thread-safe like this.

Also regarding verbose, what info did you need to see? Im guessing

1. IPC Command issued
2. Time to respond with result

Submitted by caseyboardman on Fri, 2017/09/22 - 23:50

#3

Yeah I write, wait for and read the response, and then write again. It's weird though - this log message seems to start happening when I'm not even using the machine, it's just sitting there waiting and I'm not interacting with it at all.

For verbosity, anything that would help diagnose issues that happen sporadically - I think the 2 things you list are great. Honestly, anything else that you'd like to see for a weird case like this too. I don't have anything specific in mind, just trying to get as many clues as I can.

Submitted by Michael on Mon, 2017/09/25 - 18:35

#4

Can you download 4.2.6 of the client and see if it fixes the problem.

Submitted by caseyboardman on Tue, 2017/09/26 - 23:48

#5

It looks promising. Will test some more and post here if I see it again.