Author: Jonas Devlieghere Date: 2025-03-05T08:49:49-08:00 New Revision: 6c4febee2992d206e95e2ed2294fe216739af1cb
URL: https://github.com/llvm/llvm-project/commit/6c4febee2992d206e95e2ed2294fe216739af1cb DIFF: https://github.com/llvm/llvm-project/commit/6c4febee2992d206e95e2ed2294fe216739af1cb.diff LOG: [lldb-dap] Implement a MemoryMonitor (#129332) This implements a memory monitor for macOS, Linux and Windows. It registers a callback that invokes `SBDebugger::MemoryPressureDetected` when a low memory event is detected. This is motivated by the new server mode, where the lldb-dap process will live across multiple debug sessions and will use more memory due to caching. Added: lldb/include/lldb/Host/MemoryMonitor.h lldb/source/Host/common/MemoryMonitor.cpp lldb/source/Host/macosx/objcxx/MemoryMonitorMacOSX.mm Modified: lldb/source/Host/CMakeLists.txt lldb/source/Host/macosx/objcxx/CMakeLists.txt lldb/tools/lldb-dap/lldb-dap.cpp Removed: ################################################################################ diff --git a/lldb/include/lldb/Host/MemoryMonitor.h b/lldb/include/lldb/Host/MemoryMonitor.h new file mode 100644 index 0000000000000..504f5f9cba96b --- /dev/null +++ b/lldb/include/lldb/Host/MemoryMonitor.h @@ -0,0 +1,41 @@ +//===-- MemoryMonitor.h ---------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef LLDB_HOST_MEMORYMONITOR_H +#define LLDB_HOST_MEMORYMONITOR_H + +#include <functional> +#include <memory> + +namespace lldb_private { + +class MemoryMonitor { +public: + using Callback = std::function<void()>; + + MemoryMonitor(Callback callback) : m_callback(callback) {} + virtual ~MemoryMonitor() = default; + + /// MemoryMonitor is not copyable. + /// @{ + MemoryMonitor(const MemoryMonitor &) = delete; + MemoryMonitor &operator=(const MemoryMonitor &) = delete; + /// @} + + static std::unique_ptr<MemoryMonitor> Create(Callback callback); + + virtual void Start() = 0; + virtual void Stop() = 0; + +protected: + Callback m_callback; +}; + +} // namespace lldb_private + +#endif diff --git a/lldb/source/Host/CMakeLists.txt b/lldb/source/Host/CMakeLists.txt index cdfb6184f2219..f4be151756b3b 100644 --- a/lldb/source/Host/CMakeLists.txt +++ b/lldb/source/Host/CMakeLists.txt @@ -27,6 +27,7 @@ add_host_subdirectory(common common/LockFileBase.cpp common/LZMA.cpp common/MainLoopBase.cpp + common/MemoryMonitor.cpp common/MonitoringProcessLauncher.cpp common/NativeProcessProtocol.cpp common/NativeRegisterContext.cpp @@ -136,7 +137,7 @@ else() elseif (CMAKE_SYSTEM_NAME MATCHES "AIX") add_host_subdirectory(aix aix/HostInfoAIX.cpp - ) + ) endif() endif() diff --git a/lldb/source/Host/common/MemoryMonitor.cpp b/lldb/source/Host/common/MemoryMonitor.cpp new file mode 100644 index 0000000000000..932fa9c43a22c --- /dev/null +++ b/lldb/source/Host/common/MemoryMonitor.cpp @@ -0,0 +1,109 @@ +//===-- MemoryMonitor.cpp -------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#include "lldb/Host/MemoryMonitor.h" +#include "lldb/Host/HostThread.h" +#include "lldb/Host/ThreadLauncher.h" +#include "lldb/Utility/LLDBLog.h" +#include "lldb/Utility/Log.h" +#include "llvm/ADT/ScopeExit.h" +#include "llvm/Support/Error.h" +#include <atomic> +#include <cstddef> +#include <cstdio> +#include <cstring> + +#if defined(__linux__) +#include <fcntl.h> +#include <poll.h> +#include <unistd.h> +#endif + +#if defined(_WIN32) +#include <windows.h> +#endif + +using namespace lldb_private; + +class MemoryMonitorPoll : public MemoryMonitor { +public: + using MemoryMonitor::MemoryMonitor; + + lldb::thread_result_t MonitorThread() { +#if defined(__linux__) + struct pollfd fds; + fds.fd = open("/proc/pressure/memory", O_RDWR | O_NONBLOCK); + if (fds.fd < 0) + return {}; + fds.events = POLLPRI; + + auto cleanup = llvm::make_scope_exit([&]() { close(fds.fd); }); + + // Detect a 50ms stall in a 2 second time window. + const char trig[] = "some 50000 2000000"; + if (write(fds.fd, trig, strlen(trig) + 1) < 0) + return {}; + + while (!m_done) { + int n = poll(&fds, 1, g_timeout); + if (n > 0) { + if (fds.revents & POLLERR) + return {}; + if (fds.revents & POLLPRI) + m_callback(); + } + } +#endif + +#if defined(_WIN32) + HANDLE low_memory_notification = + CreateMemoryResourceNotification(LowMemoryResourceNotification); + if (!low_memory_notification) + return {}; + + while (!m_done) { + if (WaitForSingleObject(low_memory_notification, g_timeout) == + WAIT_OBJECT_0) { + m_callback(); + } + } +#endif + + return {}; + } + + void Start() override { + llvm::Expected<HostThread> memory_monitor_thread = + ThreadLauncher::LaunchThread("lldb.debugger.memory-monitor", + [this] { return MonitorThread(); }); + if (memory_monitor_thread) { + m_memory_monitor_thread = *memory_monitor_thread; + } else { + LLDB_LOG_ERROR(GetLog(LLDBLog::Host), memory_monitor_thread.takeError(), + "failed to launch host thread: {0}"); + } + } + + void Stop() override { + if (m_memory_monitor_thread.IsJoinable()) { + m_done = true; + m_memory_monitor_thread.Join(nullptr); + } + } + +private: + static constexpr uint32_t g_timeout = 1000; + std::atomic<bool> m_done = false; + HostThread m_memory_monitor_thread; +}; + +#if !defined(__APPLE__) +std::unique_ptr<MemoryMonitor> MemoryMonitor::Create(Callback callback) { + return std::make_unique<MemoryMonitorPoll>(callback); +} +#endif diff --git a/lldb/source/Host/macosx/objcxx/CMakeLists.txt b/lldb/source/Host/macosx/objcxx/CMakeLists.txt index 1e693bed12ce1..cda8269ca9efd 100644 --- a/lldb/source/Host/macosx/objcxx/CMakeLists.txt +++ b/lldb/source/Host/macosx/objcxx/CMakeLists.txt @@ -6,6 +6,7 @@ add_lldb_library(lldbHostMacOSXObjCXX NO_PLUGIN_DEPENDENCIES Host.mm HostInfoMacOSX.mm HostThreadMacOSX.mm + MemoryMonitorMacOSX.mm LINK_LIBS lldbUtility diff --git a/lldb/source/Host/macosx/objcxx/MemoryMonitorMacOSX.mm b/lldb/source/Host/macosx/objcxx/MemoryMonitorMacOSX.mm new file mode 100644 index 0000000000000..cb6c2457df1e3 --- /dev/null +++ b/lldb/source/Host/macosx/objcxx/MemoryMonitorMacOSX.mm @@ -0,0 +1,51 @@ +//===-- MemoryMonitorMacOSX.mm --------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#include "lldb/Host/MemoryMonitor.h" +#include <cassert> +#include <dispatch/dispatch.h> + +using namespace lldb_private; + +class MemoryMonitorMacOSX : public MemoryMonitor { + using MemoryMonitor::MemoryMonitor; + void Start() override { + m_memory_pressure_source = dispatch_source_create( + DISPATCH_SOURCE_TYPE_MEMORYPRESSURE, 0, + DISPATCH_MEMORYPRESSURE_WARN | DISPATCH_MEMORYPRESSURE_CRITICAL, + dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)); + + if (!m_memory_pressure_source) + return; + + dispatch_source_set_event_handler(m_memory_pressure_source, ^{ + dispatch_source_memorypressure_flags_t pressureLevel = + dispatch_source_get_data(m_memory_pressure_source); + if (pressureLevel & + (DISPATCH_MEMORYPRESSURE_WARN | DISPATCH_MEMORYPRESSURE_CRITICAL)) { + m_callback(); + } + }); + dispatch_activate(m_memory_pressure_source); + printf("Started\n"); + } + + void Stop() override { + if (m_memory_pressure_source) { + dispatch_source_cancel(m_memory_pressure_source); + dispatch_release(m_memory_pressure_source); + } + } + +private: + dispatch_source_t m_memory_pressure_source; +}; + +std::unique_ptr<MemoryMonitor> MemoryMonitor::Create(Callback callback) { + return std::make_unique<MemoryMonitorMacOSX>(callback); +} diff --git a/lldb/tools/lldb-dap/lldb-dap.cpp b/lldb/tools/lldb-dap/lldb-dap.cpp index d005eccfae903..a5d9978e30248 100644 --- a/lldb/tools/lldb-dap/lldb-dap.cpp +++ b/lldb/tools/lldb-dap/lldb-dap.cpp @@ -10,11 +10,13 @@ #include "EventHelper.h" #include "Handler/RequestHandler.h" #include "RunInTerminal.h" +#include "lldb/API/SBDebugger.h" #include "lldb/API/SBStream.h" #include "lldb/Host/Config.h" #include "lldb/Host/File.h" #include "lldb/Host/MainLoop.h" #include "lldb/Host/MainLoopBase.h" +#include "lldb/Host/MemoryMonitor.h" #include "lldb/Host/Socket.h" #include "lldb/Utility/Status.h" #include "lldb/Utility/UriParser.h" @@ -504,9 +506,24 @@ int main(int argc, char *argv[]) { return EXIT_FAILURE; } + // Create a memory monitor. This can return nullptr if the host platform is + // not supported. + std::unique_ptr<lldb_private::MemoryMonitor> memory_monitor = + lldb_private::MemoryMonitor::Create([&]() { + if (log) + *log << "memory pressure detected\n"; + lldb::SBDebugger::MemoryPressureDetected(); + }); + + if (memory_monitor) + memory_monitor->Start(); + // Terminate the debugger before the C++ destructor chain kicks in. - auto terminate_debugger = - llvm::make_scope_exit([] { lldb::SBDebugger::Terminate(); }); + auto terminate_debugger = llvm::make_scope_exit([&] { + if (memory_monitor) + memory_monitor->Stop(); + lldb::SBDebugger::Terminate(); + }); std::vector<std::string> pre_init_commands; for (const std::string &arg : _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
