Panic: Too many open files

[antiochp]

Nothing scientific but I feel like we are seeing an increase in panics related Too many open files recently. I feel like I am seeing these pretty regularly on master right now.

This is on a small vps so its resources are pretty constrained but this did not used to happen as regularly.

thread 'peer_connect' panicked at 'clone conn for writer failed: Os { code: 24, kind: Other, message: "Too many open files" }': src/libcore/result.rs:999stack backtrace:
   0: <unknown> (0x556c3de00971)
   1: std::panicking::rust_panic_with_hook::hffcefc09751839d1 (0x556c3df2f169)
   2: <unknown> (0x556c3df2ec02)
   3: rust_begin_unwind (0x556c3df2eae6)
   4: core::panicking::panic_fmt::h2daf88b2616ca2b2 (0x556c3df4cc3d)
   5: <unknown> (0x556c3dcc925e)
   6: <unknown> (0x556c3dcf46dc)
   7: <unknown> (0x556c3dcce933)
   8: grin_p2p::peer::Peer::connect::hb6fc42afd3f9d161 (0x556c3dccf761)
   9: grin_p2p::serv::Server::connect::h333293aa8e6df115 (0x556c3dcdf645)
  10: <unknown> (0x556c3d991b7f)
  11: <unknown> (0x556c3d96a50e)
  12: __rust_maybe_catch_panic (0x556c3df3467a)
  13: <unknown> (0x556c3d8a7243)
  14: <unknown> (0x556c3df1d57f)
  15: <unknown> (0x556c3df33a30)
  16: <unknown> (0x7f251a0666ba)
  17: clone (0x7f2519b8641d)
  18: <no info> (0x0)

[antiochp]

Resolved by #3063
We were seeing these panics because we were creating a lot of peer threads that were deadlocking and not being cleaned up.