1 // Copyright 2023 The gRPC Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 #include "src/core/lib/event_engine/thread_pool/thread_count.h"
15
16 #include <grpc/support/port_platform.h>
17 #include <inttypes.h>
18
19 #include <cstddef>
20
21 #include "absl/log/log.h"
22 #include "absl/status/status.h"
23 #include "absl/strings/str_format.h"
24 #include "absl/time/clock.h"
25 #include "absl/time/time.h"
26 #include "src/core/util/time.h"
27
28 namespace grpc_event_engine {
29 namespace experimental {
30
31 // -------- LivingThreadCount --------
32
BlockUntilThreadCount(size_t desired_threads,const char * why,grpc_core::Duration stuck_timeout)33 absl::Status LivingThreadCount::BlockUntilThreadCount(
34 size_t desired_threads, const char* why,
35 grpc_core::Duration stuck_timeout) {
36 grpc_core::Timestamp timeout_baseline = grpc_core::Timestamp::Now();
37 constexpr grpc_core::Duration log_rate = grpc_core::Duration::Seconds(5);
38 size_t prev_thread_count = 0;
39 while (true) {
40 auto curr_threads = WaitForCountChange(desired_threads, log_rate / 2);
41 if (curr_threads == desired_threads) return absl::OkStatus();
42 auto elapsed = grpc_core::Timestamp::Now() - timeout_baseline;
43 if (curr_threads == prev_thread_count) {
44 if (elapsed > stuck_timeout) {
45 return absl::DeadlineExceededError(absl::StrFormat(
46 "Timed out after %f seconds", stuck_timeout.seconds()));
47 }
48 } else {
49 // the thread count has changed. Reset the timeout clock
50 prev_thread_count = curr_threads;
51 timeout_baseline = grpc_core::Timestamp::Now();
52 }
53 GRPC_LOG_EVERY_N_SEC_DELAYED_DEBUG(
54 log_rate.seconds(),
55 "Waiting for thread pool to idle before %s. (%" PRIdPTR " to %" PRIdPTR
56 "). Timing out in %0.f seconds.",
57 why, curr_threads, desired_threads,
58 (stuck_timeout - elapsed).seconds());
59 }
60 }
61
WaitForCountChange(size_t desired_threads,grpc_core::Duration timeout)62 size_t LivingThreadCount::WaitForCountChange(size_t desired_threads,
63 grpc_core::Duration timeout) {
64 size_t count;
65 auto deadline = absl::Now() + absl::Milliseconds(timeout.millis());
66 do {
67 grpc_core::MutexLock lock(&mu_);
68 count = CountLocked();
69 if (count == desired_threads) break;
70 cv_.WaitWithDeadline(&mu_, deadline);
71 } while (absl::Now() < deadline);
72 return count;
73 }
74
75 } // namespace experimental
76 } // namespace grpc_event_engine
77