Eumcoz
15th August 2012, 14:48
Hello, I am looking to design a high throughput web server(millions to billions of hits a day). Each hit is going to have to parse the http header, get information for a database, construct a response, and send out a response. I have created a server, although I don't believe I am designing it right, as it is crashing under heavy load. A simple example of my server right now is as follows:
TCPInterface::TCPInterface(QObject *parent) : QTcpServer(parent)
{
listen(QHostAddress::Any,80);
connect(this, SIGNAL(toDB(QTcpSocket*)),
App::getInstance()->getDatabase(), SLOT(fromInterface(QTcpSocket*)),
Qt::QueuedConnection);
connect(App::getInstance()->getDatabase(), SIGNAL(sendToInterface(QTcpSocket*)),
this, SLOT(fromDB(QTcpSocket*)),
Qt::QueuedConnection);
}
void TCPInterface::incomingConnection(int socket)
{
QTcpSocket *s = new QTcpSocket(this);
connect(s, SIGNAL(readyRead()), this, SLOT(readClient()));
connect(s, SIGNAL(disconnected()), this, SLOT(discardClient()));
connect(s, SIGNAL(destroyed()), this, SLOT(nullSocket()));
s->setSocketDescriptor(socket);
}
void TCPInterface::readClient()
{
QTcpSocket* socket = (QTcpSocket*)sender();
emit toDB(socket);
}
void TCPInterface::discardClient()
{
QTcpSocket* socket = qobject_cast<QTcpSocket*>(sender());
if(socket != NULL)
socket->deleteLater();
}
void TCPInterface::fromDB(QTcpSocket *socket)
{
QString tmp = "HTTP/1.0 200 Ok\r\n";
tmp += "Content-Type: text/html; charset=\"utf-8\"\r\n";
tmp += "\r\nTest\n";
if(socket != NULL && socket->isWritable() && socket->isOpen() && socket->state() == QTcpSocket::ConnectedState)
socket->write(tmp.toAscii());
if(socket != NULL && socket->state() == QTcpSocket::ConnectedState)
socket->disconnectFromHost();
}
void TCPInterface::nullSocket()
{
QTcpSocket *socket = qobject_cast<QTcpSocket*>(sender());
if(socket != NULL)
socket = NULL;
}
void DatabaseInterface::fromInterface(QTcpSocket *socket)
{
emit sendToInterface(socket);
}
I am not exactly sure what my problem is, but I believe it happens when a client disconnects from the server, and I try and use a socket that no longer exists. I do have back traces printing out, however they are not always the same, here are a few I have gotten:
Error: signal 11:
./SimpleTCPServer[0x401ce6]
/lib64/libc.so.6[0x3c14032920]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN9QIODevice5writeEPKcx+0x22)[0x7fac6b5a6d22]
./SimpleTCPServer[0x401fb6]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN7QObject5eventEP6QEvent+0x38e)[0x7fac6b62cbae]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN16QCoreApplication14notifyIntern alEP7QObjectP6QEvent+0x8c)[0x7fac6b61a30c]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN23QCoreApplicationPrivate16sendP ostedEventsEP7QObjectiP11QThreadData+0x3d3)[0x7fac6b61ebf3]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(+0x1c7cf3)[0x7fac6b64bcf3]
/lib64/libglib-2.0.so.0(g_main_context_dispatch+0x22e)[0x3c15438f0e]
/lib64/libglib-2.0.so.0[0x3c1543c938]
/lib64/libglib-2.0.so.0(g_main_context_iteration+0x7a)[0x3c1543ca3a]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN20QEventDispatcherGlib13processE ventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE+0 x73)[0x7fac6b64b833]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN10QEventLoop13processEventsE6QFl agsINS_17ProcessEventsFlagEE+0x32)[0x7fac6b618ec2]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN10QEventLoop4execE6QFlagsINS_17P rocessEventsFlagEE+0x164)[0x7fac6b619334]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN16QCoreApplication4execEv+0xb9)[0x7fac6b61efc9]
./SimpleTCPServer[0x401c95]
/lib64/libc.so.6(__libc_start_main+0xfd)[0x3c1401ecdd]
./SimpleTCPServer[0x401b59]
Error: signal 11:
SimpleTCPServer[0x4200b6]
/lib64/libc.so.6[0x3cd1232920]
SimpleTCPServer[0x444a18]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtCore.so.4(+0x89c5b)[0x7fd32140dc5b]
/lib64/libpthread.so.0[0x3cd1a07851]
/lib64/libc.so.6(clone+0x6d)[0x3cd12e76dd]
Error: signal 11:
SimpleTCPServer[0x4200b6]
/lib64/libc.so.6[0x3cd1232920]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(_ZNK15QAbstractSocket5stateEv+0x 4)[0x7fd218e85ee4]
SimpleTCPServer[0x4449fc]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtCore.so.4(+0x89c5b)[0x7fd218975c5b]
/lib64/libpthread.so.0[0x3cd1a07851]
/lib64/libc.so.6(clone+0x6d)[0x3cd12e76dd]
Error: signal 11:
SimpleTCPServer[0x4200b6]
/lib64/libc.so.6[0x3cd1232920]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(+0xba512)[0x7f576d893512]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(_ZN15QAbstractSocket19setSocketD escriptorEiNS_11SocketStateE6QFlagsIN9QIODevice12O penModeFlagEE+0xb3)[0x7f576d89fd03]
SimpleTCPServer[0x429996]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(+0xcfad8)[0x7f576d8a8ad8]
Any advice on how to redesign my server would be greatly appreciated or if you happen to know why my server is crashing.
Thank you
TCPInterface::TCPInterface(QObject *parent) : QTcpServer(parent)
{
listen(QHostAddress::Any,80);
connect(this, SIGNAL(toDB(QTcpSocket*)),
App::getInstance()->getDatabase(), SLOT(fromInterface(QTcpSocket*)),
Qt::QueuedConnection);
connect(App::getInstance()->getDatabase(), SIGNAL(sendToInterface(QTcpSocket*)),
this, SLOT(fromDB(QTcpSocket*)),
Qt::QueuedConnection);
}
void TCPInterface::incomingConnection(int socket)
{
QTcpSocket *s = new QTcpSocket(this);
connect(s, SIGNAL(readyRead()), this, SLOT(readClient()));
connect(s, SIGNAL(disconnected()), this, SLOT(discardClient()));
connect(s, SIGNAL(destroyed()), this, SLOT(nullSocket()));
s->setSocketDescriptor(socket);
}
void TCPInterface::readClient()
{
QTcpSocket* socket = (QTcpSocket*)sender();
emit toDB(socket);
}
void TCPInterface::discardClient()
{
QTcpSocket* socket = qobject_cast<QTcpSocket*>(sender());
if(socket != NULL)
socket->deleteLater();
}
void TCPInterface::fromDB(QTcpSocket *socket)
{
QString tmp = "HTTP/1.0 200 Ok\r\n";
tmp += "Content-Type: text/html; charset=\"utf-8\"\r\n";
tmp += "\r\nTest\n";
if(socket != NULL && socket->isWritable() && socket->isOpen() && socket->state() == QTcpSocket::ConnectedState)
socket->write(tmp.toAscii());
if(socket != NULL && socket->state() == QTcpSocket::ConnectedState)
socket->disconnectFromHost();
}
void TCPInterface::nullSocket()
{
QTcpSocket *socket = qobject_cast<QTcpSocket*>(sender());
if(socket != NULL)
socket = NULL;
}
void DatabaseInterface::fromInterface(QTcpSocket *socket)
{
emit sendToInterface(socket);
}
I am not exactly sure what my problem is, but I believe it happens when a client disconnects from the server, and I try and use a socket that no longer exists. I do have back traces printing out, however they are not always the same, here are a few I have gotten:
Error: signal 11:
./SimpleTCPServer[0x401ce6]
/lib64/libc.so.6[0x3c14032920]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN9QIODevice5writeEPKcx+0x22)[0x7fac6b5a6d22]
./SimpleTCPServer[0x401fb6]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN7QObject5eventEP6QEvent+0x38e)[0x7fac6b62cbae]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN16QCoreApplication14notifyIntern alEP7QObjectP6QEvent+0x8c)[0x7fac6b61a30c]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN23QCoreApplicationPrivate16sendP ostedEventsEP7QObjectiP11QThreadData+0x3d3)[0x7fac6b61ebf3]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(+0x1c7cf3)[0x7fac6b64bcf3]
/lib64/libglib-2.0.so.0(g_main_context_dispatch+0x22e)[0x3c15438f0e]
/lib64/libglib-2.0.so.0[0x3c1543c938]
/lib64/libglib-2.0.so.0(g_main_context_iteration+0x7a)[0x3c1543ca3a]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN20QEventDispatcherGlib13processE ventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE+0 x73)[0x7fac6b64b833]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN10QEventLoop13processEventsE6QFl agsINS_17ProcessEventsFlagEE+0x32)[0x7fac6b618ec2]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN10QEventLoop4execE6QFlagsINS_17P rocessEventsFlagEE+0x164)[0x7fac6b619334]
/home/root/QtSDK/Desktop/Qt/4.8.1/gcc/lib/libQtCore.so.4(_ZN16QCoreApplication4execEv+0xb9)[0x7fac6b61efc9]
./SimpleTCPServer[0x401c95]
/lib64/libc.so.6(__libc_start_main+0xfd)[0x3c1401ecdd]
./SimpleTCPServer[0x401b59]
Error: signal 11:
SimpleTCPServer[0x4200b6]
/lib64/libc.so.6[0x3cd1232920]
SimpleTCPServer[0x444a18]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtCore.so.4(+0x89c5b)[0x7fd32140dc5b]
/lib64/libpthread.so.0[0x3cd1a07851]
/lib64/libc.so.6(clone+0x6d)[0x3cd12e76dd]
Error: signal 11:
SimpleTCPServer[0x4200b6]
/lib64/libc.so.6[0x3cd1232920]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(_ZNK15QAbstractSocket5stateEv+0x 4)[0x7fd218e85ee4]
SimpleTCPServer[0x4449fc]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtCore.so.4(+0x89c5b)[0x7fd218975c5b]
/lib64/libpthread.so.0[0x3cd1a07851]
/lib64/libc.so.6(clone+0x6d)[0x3cd12e76dd]
Error: signal 11:
SimpleTCPServer[0x4200b6]
/lib64/libc.so.6[0x3cd1232920]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(+0xba512)[0x7f576d893512]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(_ZN15QAbstractSocket19setSocketD escriptorEiNS_11SocketStateE6QFlagsIN9QIODevice12O penModeFlagEE+0xb3)[0x7f576d89fd03]
SimpleTCPServer[0x429996]
/root/qt-everywhere-opensource-src-4.8.1/lib/libQtNetwork.so.4(+0xcfad8)[0x7f576d8a8ad8]
Any advice on how to redesign my server would be greatly appreciated or if you happen to know why my server is crashing.
Thank you