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Improve reliability of RequestTimesOutWhenRequestBodyNotReceivedAtSpecifiedMinimumRate (#2589) 

- Fix race condition in test code
- Addresses https://github.com/aspnet/KestrelHttpServer/issues/2539
This commit is contained in:
Mike Harder 2018-05-18 16:25:01 -07:00 committed by GitHub
parent 1951ddf6ea
commit 99a661edd6
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1 changed files with 25 additions and 2 deletions
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27
test/Kestrel.FunctionalTests/RequestBodyTimeoutTests.cs
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@ -7,7 +7,6 @@ using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core;
using Microsoft.AspNetCore.Server.Kestrel.Core.Features;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
using Microsoft.AspNetCore.Testing;
@ -37,8 +36,32 @@ namespace Microsoft.AspNetCore.Server.Kestrel.FunctionalTests
context.Features.Get<IHttpMinRequestBodyDataRateFeature>().MinDataRate =
new MinDataRate(bytesPerSecond: 1, gracePeriod: gracePeriod);
// The server must call Request.Body.ReadAsync() *before* the test sets systemClock.UtcNow (which is triggered by the
// server calling appRunningEvent.Set()). If systemClock.UtcNow is set first, it's possible for the test to fail
// due to the following race condition:
//
// 1. [test] systemClock.UtcNow += gracePeriod + TimeSpan.FromSeconds(1);
// 2. [server] Heartbeat._timer is triggered, which calls HttpConnection.Tick()
// 3. [server] HttpConnection.Tick() calls HttpConnection.CheckForReadDataRateTimeout()
// 4. [server] HttpConnection.CheckForReadDataRateTimeout() is a no-op, since _readTimingEnabled is false,
// since Request.Body.ReadAsync() has not been called yet
// 5. [server] HttpConnection.Tick() sets _lastTimestamp = timestamp
// 6. [server] Request.Body.ReadAsync() is called
// 6. [test] systemClock.UtcNow is never updated again, so server timestamp is never updated,
// so HttpConnection.CheckForReadDataRateTimeout() is always a no-op until test fails
//
// This is a pretty tight race, since the once-per-second Heartbeat._timer needs to fire between the test updating
// systemClock.UtcNow and the server calling Request.Body.ReadAsync(). But it happened often enough to cause
// test flakiness in our CI (https://github.com/aspnet/KestrelHttpServer/issues/2539).
//
// For verification, I was able to induce the race by adding a sleep in the RequestDelegate:
// appRunningEvent.Set();
// Thread.Sleep(5000);
// return context.Request.Body.ReadAsync(new byte[1], 0, 1);
var readTask = context.Request.Body.ReadAsync(new byte[1], 0, 1);
appRunningEvent.Set();
return context.Request.Body.ReadAsync(new byte[1], 0, 1);
return readTask;
}, serviceContext))
{
using (var connection = server.CreateConnection())