Fix random client failures during GC server shutdown

We need to close the GC server socket before shutting down the active
GC client connections, otherwise a client may (re)connect and get
ECONNRESET. But also handle ECONNRESET for resilience.

Fixes random failures like

  GC socket disconnected
  connecting to '/tmp/nix-shell.y07M0H/nix-test/default/var/nix/gc-socket/socket'
  sending GC root '/tmp/nix-shell.y07M0H/nix-test/default/store/kb5yzija0f1x5xkqkgclrdzldxj6nnc6-non-blocking'
  reading GC root from client: error: unexpected EOF reading a line
  1 store paths deleted, 0.00 MiB freed
  error: reading from file: Connection reset by peer

in gc-non-blocking.sh.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index 9ef8972f3..5d91829f1 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -147,7 +147,7 @@ void LocalStore::addTempRoot(const StorePath & path)
         } catch (SysError & e) {
             /* The garbage collector may have exited, so we need to
                restart. */
-            if (e.errNo == EPIPE) {
+            if (e.errNo == EPIPE || e.errNo == ECONNRESET) {
                 debug("GC socket disconnected");
                 state->fdRootsSocket.close();
                 goto restart;
@@ -506,6 +506,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
         Finally cleanup([&]() {
             debug("GC roots server shutting down");
+            fdServer.close();
             while (true) {
                 auto item = remove_begin(*connections.lock());
                 if (!item) break;