C中Logger线程的线程安全队列

Question

So, I have a MMO game server listening for connections (up to 1100, hardcoded limit because of game design) and needing to log everything without blocking my main thread (which handles all the virtual-world logic), including but not limited to: what NPCs give to players, when a monster/player dies, every single chat message, when players level up, when players drop an item to the ground, etc.

I get a thread from a pool for each connection, and each thread can log to a file at any time (it may actually never happen, but the server must be prepared enough to handle it appropriately).

I thought about an independent logging thread constantly checking an order queue, until it is not empty.

while Game is Running
    Check the queue, if it's empty, sleep.
    File IO. Open plain-text file, log and gracefully close it.
    Repeat.

Is a linked list enough for organizing the queue and just protect it with a mutex like this?

LogThreadOrder Queue[1024];

LogThreadOrder *FirstThreadOrder;
int NumberOfOrders;

struct LogThreadOrder {
    char FileName[4096];
    char LogMessage[4096];
    LogThreadOrder* NextOrder;
};

void Log(const char* FileName, const char* LogMessage) {
    LogMutex.lock();

    ProtocolThreadOrder* Order = Queue[NumberOfOrders++];
    Order->NextOrder = FirstThreadOrder;
    FirstThreadOrder = Order;

    LogMutex.release();

}


int LogThreadLoop() {
    // Loop through Queue until its empty.
}

So, my question is:

• Is this a smart design?

• Is it thread-safe?

• Is there any better way of accomplishing what I'm trying to do?

• Would it be better/more-efficient to have multiple logger threads and multiple queues?

Answer 1

Your pseudocode could be made to work, but it's difficult in C and mutex synchronization is inefficient. In my experience it's always better to use existing, well-established, asynchronous inter-process communication mechanisms between threads like named pipes . Even then there are many pitfalls and when dependencies aren't a problem using something like ZeroMQ might be the best idea. Specifically something like this . I don't think having multiple threads is a good idea, as file you want to write to will be a contention point.