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Implement join with timeout (and detach).

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Under certain situations (notably JNI shutdown), it's possible to get
deadlock when using thread join().  To avoid this, implement a timeout.
Normally we try to simply join the thread, but if it times out, we
detach the thread instead.
This commit is contained in:
Peter Johnson
2015-10-09 23:50:01 -07:00
parent d77b3d788e
commit dd0e3e4abb
8 changed files with 166 additions and 12 deletions
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47
src/NetworkConnection.cpp
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@@ -42,6 +42,12 @@ void NetworkConnection::Start() {
m_state = static_cast<int>(kInit);
// clear queue
while (!m_outgoing.empty()) m_outgoing.pop();
// reset shutdown flags
{
std::lock_guard<std::mutex> lock(m_shutdown_mutex);
m_read_shutdown = false;
m_write_shutdown = false;
}
// start threads
m_write_thread = std::thread(&NetworkConnection::WriteThreadMain, this);
m_read_thread = std::thread(&NetworkConnection::ReadThreadMain, this);
@@ -54,9 +60,27 @@ void NetworkConnection::Stop() {
if (m_stream) m_stream->close();
// send an empty outgoing message set so the write thread terminates
m_outgoing.push(Outgoing());
// wait for threads to terminate
if (m_write_thread.joinable()) m_write_thread.join();
if (m_read_thread.joinable()) m_read_thread.join();
// wait for threads to terminate, with timeout
if (m_write_thread.joinable()) {
std::unique_lock<std::mutex> lock(m_shutdown_mutex);
auto timeout_time =
std::chrono::steady_clock::now() + std::chrono::milliseconds(200);
if (m_write_shutdown_cv.wait_until(lock, timeout_time,
[&] { return m_write_shutdown; }))
m_write_thread.join();
else
m_write_thread.detach(); // timed out, detach it
}
if (m_read_thread.joinable()) {
std::unique_lock<std::mutex> lock(m_shutdown_mutex);
auto timeout_time =
std::chrono::steady_clock::now() + std::chrono::milliseconds(200);
if (m_read_shutdown_cv.wait_until(lock, timeout_time,
[&] { return m_read_shutdown; }))
m_read_thread.join();
else
m_read_thread.detach(); // timed out, detach it
}
// clear queue
while (!m_outgoing.empty()) m_outgoing.pop();
}
@@ -95,7 +119,7 @@ void NetworkConnection::ReadThreadMain() {
})) {
m_state = static_cast<int>(kDead);
m_active = false;
return;
goto done;
}
m_state = static_cast<int>(kActive);
@@ -122,6 +146,14 @@ void NetworkConnection::ReadThreadMain() {
m_state = static_cast<int>(kDead);
m_active = false;
m_outgoing.push(Outgoing()); // also kill write thread
done:
// use condition variable to signal thread shutdown
{
std::lock_guard<std::mutex> lock(m_shutdown_mutex);
m_read_shutdown = true;
m_read_shutdown_cv.notify_one();
}
}
void NetworkConnection::WriteThreadMain() {
@@ -153,6 +185,13 @@ void NetworkConnection::WriteThreadMain() {
m_state = static_cast<int>(kDead);
m_active = false;
if (m_stream) m_stream->close(); // also kill read thread
// use condition variable to signal thread shutdown
{
std::lock_guard<std::mutex> lock(m_shutdown_mutex);
m_write_shutdown = true;
m_write_shutdown_cv.notify_one();
}
}
void NetworkConnection::QueueOutgoing(std::shared_ptr<Message> msg) {