77a9b5919b
This commit adds a call to `pthread_setname_np` in `alien_worker::spawn`, so each alien worker thread receives a descriptive name. This makes debugging, monitoring, and performance analysis easier by allowing alien workers to be clearly identified in tools such as `perf`.
71 lines
2.1 KiB
C++
71 lines
2.1 KiB
C++
/*
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* Copyright (C) 2024-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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*/
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#include "utils/alien_worker.hh"
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#include <seastar/util/log.hh>
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using namespace seastar;
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namespace utils {
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std::thread alien_worker::spawn(seastar::logger& log, int niceness, const seastar::sstring& name_suffix) {
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sigset_t newset;
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sigset_t oldset;
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sigfillset(&newset);
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auto r = ::pthread_sigmask(SIG_SETMASK, &newset, &oldset);
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assert(r == 0);
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auto thread_name = fmt::format("alien-{}", name_suffix);
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if (thread_name.size() > 15) {
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log.warn("Thread name '{}' is longer than 15 characters, truncating to fit", thread_name);
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thread_name.resize(15); // pthread_setname_np requires name to be <= 15 characters
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}
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auto thread = std::thread([this, &log, niceness, thread_name] () noexcept {
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errno = 0;
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int setname_value = pthread_setname_np(pthread_self(), thread_name.c_str());
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if (setname_value != 0) {
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log.error("Unable to set worker thread name '{}', setname_value={}", thread_name, setname_value);
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std::abort();
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}
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int nice_value = nice(niceness);
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if (nice_value == -1 && errno != 0) {
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log.warn("Unable to renice worker thread (system error number {}); the thread will compete with reactor, which can cause latency spikes. Try adding CAP_SYS_NICE", errno);
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}
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while (true) {
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std::unique_lock lk(_mut);
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_cv.wait(lk, [this] { return !_pending.empty() || !_running; });
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if (!_running) {
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return;
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}
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auto f = std::move(_pending.front());
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_pending.pop();
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lk.unlock();
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f();
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}
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});
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r = ::pthread_sigmask(SIG_SETMASK, &oldset, nullptr);
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assert(r == 0);
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return thread;
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}
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alien_worker::alien_worker(seastar::logger& log, int niceness, const seastar::sstring& name_suffix)
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: _thread(spawn(log, niceness, name_suffix))
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{}
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alien_worker::~alien_worker() {
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{
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std::unique_lock lk(_mut);
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_running = false;
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}
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_cv.notify_one();
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_thread.join();
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}
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} // namespace utils
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