Use syncpool for chunk buffer

[tobbe76]

This reduces the number of gc:s and improves performance.
I have tested this change on our production server with good result.

[mostynb]

I wonder if we could simplify this to just return slices, instead of pointers to slices?

[tobbe76]

I have simplified it now. And the number of gc allocations is still the same in my stress test.

The reason why i used a ptr was from this thread, but to my understanding now when reading it again, it's a very small optimization using a ptr.
golang/go#16323

[mostynb]

Hmm, looks like there's a lint failure that wants us to use pointer types after all: https://staticcheck.dev/docs/checks#SA6002

Sorry- can you change that part back (and drop the third argument to make)?

[mostynb]

Landed this change, though I removed the nil check in the defer statement (it seems unnecessary). Thanks again.

BTW, I notice that you're also in Göteborg according to github :) I wonder if you could share some approximate details of your bazel-remote install? I'm always looking for feedback on how people are using it.