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From 46d14515c3105e4e318d28db41057d9f1df3ce4d Mon Sep 17 00:00:00 2001
From: Harald Sitter <sitter@kde.org>
Date: Mon, 11 Sep 2023 07:05:52 +0200
Subject: [PATCH] flatpak: make FlatpakTransactionThread a qrunnable instead
we can't just have an unlimited number of threads for flatpak
transactions. it'd eventually cause excessive load on both CPU and
network to the point where things will start misbehaving. we also run
risk of exhausting other software limited resources such as file
descriptors.
to resolve this problem we now treat the transactionthread as runnable
and put it in a limited threadpool for concurrent execution. the new
runnable has a finished signal that is emitted on every return from
run() to match the QThread API.
concurrency is limited to no more than 4 runnables at a time. that
should still be plenty concurrent while generally unexpected to exhaust
the default 1024 file descriptor limit - an install transaction appears
to weigh between 60 and 100 fds
other backends don't necessarily have this problem since they have
daemons that do the work for us so we have way fewer open fds for them.
BUG: 474231
(cherry picked from commit db0ebc855517f189f64c1602a5d27e185cf02833)
---
.../FlatpakBackend/FlatpakJobTransaction.cpp | 34 ++++++++++++++++---
.../FlatpakTransactionThread.cpp | 9 +++--
.../FlatpakBackend/FlatpakTransactionThread.h | 5 ++-
3 files changed, 40 insertions(+), 8 deletions(-)
diff --git a/libdiscover/backends/FlatpakBackend/FlatpakJobTransaction.cpp b/libdiscover/backends/FlatpakBackend/FlatpakJobTransaction.cpp
index 613563755..b2c1fcc20 100644
--- a/libdiscover/backends/FlatpakBackend/FlatpakJobTransaction.cpp
+++ b/libdiscover/backends/FlatpakBackend/FlatpakJobTransaction.cpp
@@ -1,6 +1,7 @@
/*
* SPDX-FileCopyrightText: 2013 Aleix Pol Gonzalez <aleixpol@blue-systems.com>
* SPDX-FileCopyrightText: 2017 Jan Grulich <jgrulich@redhat.com>
+ * SPDX-FileCopyrightText: 2023 Harald Sitter <sitter@kde.org>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
@@ -10,9 +11,30 @@
#include "FlatpakResource.h"
#include "FlatpakTransactionThread.h"
+#include <thread>
+
#include <QDebug>
#include <QTimer>
+namespace
+{
+class ThreadPool : public QThreadPool
+{
+public:
+ ThreadPool()
+ {
+ // Cap the amount of concurrency to prevent too many in-flight transactions. This in particular
+ // prevents running out of file descriptors or other limited resources.
+ // https://bugs.kde.org/show_bug.cgi?id=474231
+ constexpr auto arbitraryMaxConcurrency = 4U;
+ const auto concurrency = std::min(std::thread::hardware_concurrency(), arbitraryMaxConcurrency);
+ setMaxThreadCount(std::make_signed_t<decltype(concurrency)>(concurrency));
+ }
+};
+} // namespace
+
+Q_GLOBAL_STATIC(ThreadPool, s_pool);
+
FlatpakJobTransaction::FlatpakJobTransaction(FlatpakResource *app, Role role, bool delayStart)
: Transaction(app->backend(), app, role, {})
, m_app(app)
@@ -27,11 +49,12 @@ FlatpakJobTransaction::FlatpakJobTransaction(FlatpakResource *app, Role role, bo
FlatpakJobTransaction::~FlatpakJobTransaction()
{
- if (m_appJob->isRunning()) {
- cancel();
- m_appJob->wait();
+ cancel();
+ if (s_pool->tryTake(m_appJob)) { // immediately delete if the runnable hasn't started yet
+ delete m_appJob;
+ } else { // otherwise defer cleanup to the pool
+ m_appJob->setAutoDelete(true);
}
- delete m_appJob;
}
void FlatpakJobTransaction::cancel()
@@ -45,6 +68,7 @@ void FlatpakJobTransaction::start()
// App job will be added every time
m_appJob = new FlatpakTransactionThread(m_app, role());
+ m_appJob->setAutoDelete(false);
connect(m_appJob, &FlatpakTransactionThread::finished, this, &FlatpakJobTransaction::finishTransaction);
connect(m_appJob, &FlatpakTransactionThread::progressChanged, this, &FlatpakJobTransaction::setProgress);
connect(m_appJob, &FlatpakTransactionThread::speedChanged, this, &FlatpakJobTransaction::setDownloadSpeed);
@@ -52,7 +76,7 @@ void FlatpakJobTransaction::start()
connect(m_appJob, &FlatpakTransactionThread::webflowStarted, this, &FlatpakJobTransaction::webflowStarted);
connect(m_appJob, &FlatpakTransactionThread::webflowDone, this, &FlatpakJobTransaction::webflowDone);
- m_appJob->start();
+ s_pool->start(m_appJob);
}
void FlatpakJobTransaction::finishTransaction()
diff --git a/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.cpp b/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.cpp
index 7072460ad..738a97a8c 100644
--- a/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.cpp
+++ b/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.cpp
@@ -1,5 +1,6 @@
/*
* SPDX-FileCopyrightText: 2017 Jan Grulich <jgrulich@redhat.com>
+ * SPDX-FileCopyrightText: 2023 Harald Sitter <sitter@kde.org>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
@@ -10,6 +11,7 @@
#include <KLocalizedString>
#include <QDebug>
#include <QDesktopServices>
+#include <QScopeGuard>
static int FLATPAK_CLI_UPDATE_FREQUENCY = 150;
@@ -92,8 +94,7 @@ void FlatpakTransactionThread::webflowDoneCallback(FlatpakTransaction *transacti
}
FlatpakTransactionThread::FlatpakTransactionThread(FlatpakResource *app, Transaction::Role role)
- : QThread()
- , m_result(false)
+ : m_result(false)
, m_app(app)
, m_role(role)
{
@@ -131,6 +132,10 @@ void FlatpakTransactionThread::cancel()
void FlatpakTransactionThread::run()
{
+ auto finish = qScopeGuard([this] {
+ Q_EMIT finished();
+ });
+
if (!m_transaction)
return;
g_autoptr(GError) localError = nullptr;
diff --git a/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.h b/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.h
index 277c21902..8e3d0e2e2 100644
--- a/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.h
+++ b/libdiscover/backends/FlatpakBackend/FlatpakTransactionThread.h
@@ -1,5 +1,6 @@
/*
* SPDX-FileCopyrightText: 2017 Jan Grulich <jgrulich@redhat.com>
+ * SPDX-FileCopyrightText: 2023 Harald Sitter <sitter@kde.org>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
@@ -11,12 +12,13 @@
#include <glib.h>
#include <QMap>
+#include <QRunnable>
#include <QStringList>
#include <QThread>
#include <Transaction/Transaction.h>
class FlatpakResource;
-class FlatpakTransactionThread : public QThread
+class FlatpakTransactionThread : public QObject, public QRunnable
{
Q_OBJECT
public:
@@ -49,6 +51,7 @@ Q_SIGNALS:
void passiveMessage(const QString &msg);
void webflowStarted(const QUrl &url, int id);
void webflowDone(int id);
+ void finished();
private:
static gboolean
--
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