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f0aa540e00
The Wasm compilation is a slow, low priority task, so it should not compete with reactor threads or the networking core. To achieve that, we increase the niceness of the thread by 10. An alternative solution would be to set the priority using pthread_setschedparam, but it's not currently feasible, because as long as we're using the SCHED_OTHER policy for our threads, we cannot select any other priority than 0. Closes #13307
85 lines
2.5 KiB
C++
85 lines
2.5 KiB
C++
/*
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* Copyright (C) 2023-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#include <exception>
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#include <seastar/core/alien.hh>
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#include <seastar/core/posix.hh>
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#include <seastar/core/reactor.hh>
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#include <unistd.h>
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#include "log.hh"
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#include "lang/wasm.hh"
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#include "lang/wasm_alien_thread_runner.hh"
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#include "seastar/core/posix.hh"
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extern logging::logger wasm_logger;
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namespace wasm {
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std::optional<wasm_compile_task> task_queue::pop_front() {
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std::unique_lock lock(_mut);
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_cv.wait(lock, [this] { return !_pending.empty(); });
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auto work_item = std::move(_pending.front());
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_pending.pop();
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return work_item;
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}
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void task_queue::push_back(std::optional<wasm_compile_task> work_item) {
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std::unique_lock lock(_mut);
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_pending.emplace(std::move(work_item));
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lock.unlock();
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_cv.notify_one();
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}
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alien_thread_runner::alien_thread_runner()
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: _thread([this] {
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sigset_t mask;
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sigfillset(&mask);
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auto r = ::pthread_sigmask(SIG_BLOCK, &mask, nullptr);
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throw_pthread_error(r);
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errno = 0;
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int nice_value = nice(10);
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if (nice_value == -1 && errno != 0) {
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wasm_logger.warn("Unable to renice the alien thread (system error number {}); the thread will compete with reactor. Try adding CAP_SYS_NICE", errno);
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}
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for (;;) {
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auto work_item = _pending_queue.pop_front();
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if (work_item) {
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work_item->func();
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} else {
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break;
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}
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}
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})
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{ }
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alien_thread_runner::~alien_thread_runner() {
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_pending_queue.push_back(std::nullopt);
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_thread.join();
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}
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void alien_thread_runner::submit(seastar::promise<rust::Box<wasmtime::Module>>& p, std::function<rust::Box<wasmtime::Module>()> f) {
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seastar::noncopyable_function<void()> packaged([f = std::move(f), &p, &alien = seastar::engine().alien(), shard = seastar::this_shard_id()] () mutable {
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try {
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rust::Box<wasmtime::Module> mod = f();
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seastar::alien::run_on(alien, shard, [&p, mod = std::move(mod)] () mutable {
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p.set_value(std::move(mod));
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});
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} catch (...) {
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seastar::alien::run_on(alien, shard, [&, eptr = std::current_exception()] {
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p.set_exception(wasm::exception(format("Compilation failed: {}", eptr)));
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});
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}
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});
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_pending_queue.push_back(wasm_compile_task{.func = std::move(packaged), .done = p, .shard = seastar::this_shard_id()});
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}
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} // namespace wasm
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