Swarm Failed To Kick Off - File In Use By Process

Hello all, Have a slight problem since installing 4.2 this morning.
When I go to build lighting I get a message that Swarm has failed to kick off, checking my taskbar swarm is running and the log shows this message:

[1:46:09 PM] Dylan Browne: 1:45:45 PM: [Interface:OpenChannel] Error: System.IO.IOException: The process cannot access the file 'C:\Users\Dylza\AppData\Local\UnrealEngine\4.2\Saved\Swarm\SwarmCache\AgentStagingArea\A6630D7233BF47B3BBCF76BB4350A2B5.00000000000000000000000000000000.mtrlgz' because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
   at NSwarm.FSwarmInterface.OpenChannel(String ChannelName, EChannelFlags ChannelFlags)

Checked the file permissions which are all good, restarted my machine, removed the files in the AgentStagingArea folder, used process explorer to find out what is locking the file (according to that no process is locking it).
Any suggestions on what is going on here?
4.1 works fine aha.

Hi DylserX -

I wanted to get some more information about the project you are trying to build. What version of the engine are you using, is this a compiled source version of the engine from Github or is this the Launcher version? Also the project itself, is it a code based project, blueprint based, or is it one of our sample levels?

Thank You

Eric Ketchum

Hi Eric,
I am using 4.2.0 Launcher Version and the project is Blueprint based.
Cheers
Dylan

Hello,
I’m experiencing the same problem described in this page.
Swarm stopped working on all our machines giving on each one of them the same cache file access problem.
Removed cache folders after a reboot, but nothing.
Tried with both 4.1 (previously working) and 4.2: they are both broken in the same way.

The project I’m working on is a new one and it is blueprint based.
Thanks

Hi DylserX and Budello -

Can you both provide us with your system specs and whether you are attempting to build lighting using more than 1 CPU or over a network?

Thank You

Eric Ketchum

No problem Eric,
No network rendering or multiple CPU’s here.

Windows 8.1 Pro (64-bit)
AMD FX-8120 Eight-Core CPU @ 3.1Ghz
16GB DDR3 Ram (1600mhz)
AMD HD 6970 2GB GPU

Cheers
Dylan

Here you have two of our configurations:

Windows 8.1 pro 64-bit
i7-4770
16 GB
GTX 780 Ti

Windows 8.1 pro 64-bit
i7-3770k
16Gb GB
GTX 660 Ti

Some maps just work fine, but on our main map is crashing. We’ve tried to clean our cache, to enlarge it and to move it on another drive, with no result: we’re always getting the error at the beginning of this thread.

Peace,
Budello

Hey -

We are still trying to track down this issue can you upload a copy of your DXDIAG?

Thank You

Eric Ketchum

Hello!

Apparently we fixed our problem scaling the entire level to approximately 0.35 of the original size. After that the light building process ran flawlessly. Before the scaling our world terrain was covering a squared surface of 400k unreal units side (world settings → world to meters = 100).

Is there any guideline to be followed about the scaling and the limit amount of object in the scene to run lightmass?

Example question: In our map we have a lot of manually placed trees, plants and rocks, each one with a different scale ranging from 1 to 15.

Do you know if it is computational lighter to use the foliage brush on landscape for distributing these meshes on the terrain? Could this manual placement be related to the swarm failed to kick off problem?

Hope this can help

Peace, Budello

Edit:
Forgot to upload the DXDIAG information log as requested:

Here is my dxdiag :), I will give the scaling a go tomorrow aha dxdiag - Pastebin.com

Nothing I have tried has worked yet, scaling isn’t really an option since my level is small anyway.

LIVE NEWS:

apparently, scaling the map fixed the problem only on two of our PCs, with these configurations:

Windows 8.1 pro 64-bit i7-4770 16 GB GTX 780 Ti

Windows 8.1 pro 64-bit i7-3770k 16Gb GB GTX 660 Ti

On the third one

Windows 8.1 pro 64-bit Q9650 8Gb GB Radeon HD 5800 Series

continues to fail. We may think is a RAM problem, cause this one has 8 Gb “only”.

We actually don’t know how to cope with this issue…

Peace,
Budello

Hey DylserX -

I want to check in to see if this is still a persistent problem for you and to if it is to ask you to try copying your level assets, except the lighting into an another map and try building this new map. If this build goes successfully go back to you original map file and try building your lights again.

Let me know -

Eric Ketchum

Hi Eric, I gave it a try and low and behold It worked! , I copied it all over except the lighting, and re-lit in the new map and it is now working. Thank You! Saved me some work there!