Mill Client-Daemon mode hanging in WSL2 Ubuntu 18.04

[lihaoyi]

As far as I can tell so far, this is because the following code that tries to get a file lock fails silently on WSL2 Ubuntu:

val raf = new java.io.RandomAccessFile("/home/ubuntu/hello", "rw")
val chan = raf.getChannel
val lock = chan.tryLock()

I can run this in two separate Ammonite REPLs and both of them will claim to successfully take the lock. In contrast, doing this on OS-X or a proper Ubuntu machine will have the second call to tryLock() return null.

This ends up confusing the client-server handshake, where the client waits for the server to claim the processLock to indicate that it is up and running: since the client always sees the lock as free, it thinks the server never starts and just hangs

Seems to be caused by this underlying issue: microsoft/WSL#1927

[edrevo]

Just FYI, according to microsoft/WSL#1927 (comment) locks are working fine in WSL2, so the root cause might be something else.

[sake92]

Seems to work now, maybe #1230 fixed it.. 😄

sake@DESKTOP-4KROVCU:/mnt/c/scala/mill/0.9.9/example-1$ ../mill-0.9.9.bat foo.compile
Preparing Java 11.0.11 runtime; this may take a minute or two ...
Compiling /mnt/c/scala/mill/0.9.9/example-1/build.sc
[26/26] foo.compile
[info] compiling 1 Scala source to /mnt/c/scala/mill/0.9.9/example-1/out/foo/compile/dest/classes ...
[info] done compiling
sake@DESKTOP-4KROVCU:/mnt/c/scala/mill/0.9.9/example-1$ ../mill-0.9.9.bat foo.run
[39/39] foo.run
Hello World

[lefou]

Probably fixed by #2901.