Controller SQL 数据库中的异步/等待死锁

Question

I have a controller receiving multiple POST (1000 per minute) from multiple machines and due to that all these data are not inserted in the SQL database and generate some deadlocks.

How can I lock this method to be used synchronously to insert one after one instead of all at same time?

I am able to reproduce the issue with this test controller:

[HttpPost]
public async Task<ActionResult> Create([Bind(Include = "Value1,Value2,Id")] Test test)
{
    if (ModelState.IsValid)
    {
        db.Tests.Add(test);
        await db.SaveChangesAsync();
    }

    return new EmptyResult();
}

EDIT: This code worked like a charm thanks to Peter answer. No deadlock. Performance was good and no slowness noticed.

private SemaphoreSlim _semaphore = new SemaphoreSlim(1);

[HttpPost]
public async Task<ActionResult> Create([Bind(Include = "Value1,Value2,Id")] Test test)
{
    await _semaphore.WaitAsync();

    if (ModelState.IsValid)
    {
        db.Tests.Add(test);
        await db.SaveChangesAsync().ConfigureAwait(false);
    }

    _semaphore.Release();
    db.Dispose();

    return new EmptyResult();
}

Answer 1

You could use a SemaphoreSlim to limit the access to the database. This Semaphore can be awaited asynchously.

SemaphoreSlim semaphore = new SemaphoreSlim(1,1);    

public async Task<ActionResult> Create([Bind(Include = "Value1,Value2,Id")] Test test)
{
    try{
        await semaphore.WaitAsync().ConfigureAwait(false);
        if (ModelState.IsValid)
        {
            db.AuditTests.Add(test);
            await db.SaveChangesAsync().ConfigureAwait(false);
        }
    }finally{
        semaphore.release();
    }
    return new EmptyResult();
}

try - finally is used to make sure the lock is always released, even if eg the database call fails.