fork of https://github.com/sourcegraph/zoekt
webserver: shutdown via close if using RPC (#516)
Our RPC system does not support shutdown and hijacks the underlying http
connection. This means shutdown is ineffective and just waits 10s before
calling close. Lets just quit faster in that case.
Test Plan: Run zoekt-webserver with and without rpc. Run kill and
observe behaviour.
author
Keegan Carruthers-Smith
committer
GitHub
date
(Jan 10, 2023, 3:19 PM +0200)
commit
38d5f90f
38d5f90fb112336b7d341e0d6fadfb885016a0ab
parent
5bbffb3c
5bbffb3cc3e860887d81717cc375fa7784cf0cf6
+36
-8
+36
-8
cmd/zoekt-webserver/main.go
+36
-8
cmd/zoekt-webserver/main.go
···
299
299
}
300
300
}()
301
301
302
-
if err := shutdownOnSignal(srv); err != nil {
303
-
log.Fatalf("http.Server.Shutdown: %v", err)
302
+
if s.RPC {
303
+
// Our RPC system does not support shutdown and hijacks the underlying
304
+
// http connection. This means shutdown is ineffective and just waits 10s
305
+
// before calling close. Lets just quit faster in that case.
306
+
if err := closeOnSignal(srv); err != nil {
307
+
log.Fatalf("http.Server.Close: %v", err)
308
+
}
309
+
} else {
310
+
if err := shutdownOnSignal(srv); err != nil {
311
+
log.Fatalf("http.Server.Shutdown: %v", err)
312
+
}
304
313
}
305
314
}
306
315
···
322
331
mux.Handle("/indexserver/", http.StripPrefix("/indexserver/", http.HandlerFunc(proxy.ServeHTTP)))
323
332
}
324
333
325
-
// shutdownOnSignal will listen for SIGINT or SIGTERM and call
326
-
// srv.Shutdown. Note it doesn't call anything else for shutting down. Notably
327
-
// our RPC framework doesn't allow us to drain connections, so it when
328
-
// Shutdown is called all inflight RPC requests will be closed.
329
-
func shutdownOnSignal(srv *http.Server) error {
330
-
c := make(chan os.Signal, 3)
334
+
// shutdownSignalChan returns a channel which is listening for shutdown
335
+
// signals from the operating system. maxReads is an upper bound on how many
336
+
// times you will read the channel (used as buffer for signal.Notify).
337
+
func shutdownSignalChan(maxReads int) <-chan os.Signal {
338
+
c := make(chan os.Signal, maxReads)
331
339
signal.Notify(c, os.Interrupt) // terminal C-c and goreman
332
340
signal.Notify(c, syscall.SIGTERM) // Kubernetes
341
+
return c
342
+
}
333
343
344
+
// closeOnSignal will listen for SIGINT or SIGTERM and call srv.Close. This is
345
+
// not a graceful shutdown, see shutdownOnSignal.
346
+
func closeOnSignal(srv *http.Server) error {
347
+
c := shutdownSignalChan(1)
348
+
<-c
349
+
350
+
return srv.Close()
351
+
}
352
+
353
+
// shutdownOnSignal will listen for SIGINT or SIGTERM and call srv.Shutdown.
354
+
// Note it doesn't call anything else for shutting down. Notably our RPC
355
+
// framework doesn't allow us to drain connections, so when Shutdown we will
356
+
// wait 10s before closing.
357
+
//
358
+
// Note: the call site for shutdownOnSignal should use closeOnSignal instead
359
+
// if rpc mode is enabled due to the above limitation.
360
+
func shutdownOnSignal(srv *http.Server) error {
361
+
c := shutdownSignalChan(2)
334
362
<-c
335
363
336
364
// If we receive another signal, immediate shutdown