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Fix PythonAnalyzerSession leak #866

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Apr 2, 2019
Merged

Fix PythonAnalyzerSession leak #866

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54 changes: 45 additions & 9 deletions src/Analysis/Ast/Impl/Analyzer/PythonAnalyzer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Python.Analysis.Dependencies;
Expand All @@ -39,17 +40,20 @@ public sealed class PythonAnalyzer : IPythonAnalyzer, IDisposable {
private readonly DisposeToken _disposeToken = DisposeToken.Create<PythonAnalyzer>();
private readonly object _syncObj = new object();
private readonly AsyncManualResetEvent _analysisCompleteEvent = new AsyncManualResetEvent();
private readonly Action<Task> _startNextSession;
private readonly ProgressReporter _progress;
private readonly ILogger _log;
private readonly int _maxTaskRunning = Environment.ProcessorCount;
private int _version;
private PythonAnalyzerSession _session;
private PythonAnalyzerSession _currentSession;
private PythonAnalyzerSession _nextSession;

public PythonAnalyzer(IServiceManager services) {
_services = services;
_log = services.GetService<ILogger>();
_dependencyResolver = new DependencyResolver<AnalysisModuleKey, PythonAnalyzerEntry>();
_analysisCompleteEvent.Set();
_startNextSession = StartNextSession;

_progress = new ProgressReporter(services.GetService<IProgressService>());
}
Expand Down Expand Up @@ -195,24 +199,56 @@ private void AnalyzeDocument(AnalysisModuleKey key, PythonAnalyzerEntry entry, I
LoadMissingDocuments(entry.Module.Interpreter, walker.MissingKeys);
}

PythonAnalyzerSession currentSession, nextSession;
if (TryCreateSession(walker, entry, cancellationToken, out var session)) {
session.Start(true);
}
}

private bool TryCreateSession(IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> walker, PythonAnalyzerEntry entry, CancellationToken cancellationToken, out PythonAnalyzerSession session) {
lock (_syncObj) {
currentSession = _session;
if (currentSession != null && currentSession.Version > walker.Version) {
return;
if (_currentSession == null) {
_currentSession = session = CreateSession(walker, null, cancellationToken);
return true;
}

if (_currentSession.Version > walker.Version || _nextSession != null && _nextSession.Version > walker.Version) {
session = null;
return false;
}

if (_version > walker.Version && (!_currentSession.IsCompleted || walker.AffectedValues.GetCount(e => e.NotAnalyzed) < _maxTaskRunning)) {
session = null;
return false;
}

if (_currentSession.IsCompleted) {
_currentSession = session = CreateSession(walker, null, cancellationToken);
return true;
}

if (_version > walker.Version && currentSession != null && (!currentSession.IsCompleted || walker.AffectedValues.GetCount(e => e.NotAnalyzed) < _maxTaskRunning)) {
_currentSession.Cancel();
_nextSession = session = CreateSession(walker, entry.IsUserModule ? entry : null, cancellationToken);
return entry.IsUserModule;
}
}

private void StartNextSession(Task task) {
PythonAnalyzerSession session;
lock (_syncObj) {
if (_nextSession == null) {
return;
}

nextSession = new PythonAnalyzerSession(_services, _progress, _analysisCompleteEvent, _disposeToken.CancellationToken, cancellationToken, walker, _version);
_session = nextSession;
_currentSession = session = _nextSession;
_nextSession = null;
}

nextSession.Start(currentSession, entry);
session.Start(false);
}

private PythonAnalyzerSession CreateSession(IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> walker, PythonAnalyzerEntry entry, CancellationToken cancellationToken)
=> new PythonAnalyzerSession(_services, _progress, _analysisCompleteEvent, _startNextSession, _disposeToken.CancellationToken, cancellationToken, walker, _version, entry);

private void LoadMissingDocuments(IPythonInterpreter interpreter, ImmutableArray<AnalysisModuleKey> missingKeys) {
foreach (var (moduleName, _, isTypeshed) in missingKeys) {
var moduleResolution = isTypeshed ? interpreter.TypeshedResolution : interpreter.ModuleResolution;
Expand Down
145 changes: 52 additions & 93 deletions src/Analysis/Ast/Impl/Analyzer/PythonAnalyzerSession.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,6 @@
// permissions and limitations under the License.

using System;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Threading;
Expand All @@ -25,7 +24,6 @@
using Microsoft.Python.Analysis.Modules;
using Microsoft.Python.Analysis.Types;
using Microsoft.Python.Core;
using Microsoft.Python.Core.Diagnostics;
using Microsoft.Python.Core.Logging;
using Microsoft.Python.Core.Services;
using Microsoft.Python.Parsing.Ast;
Expand All @@ -34,21 +32,21 @@ namespace Microsoft.Python.Analysis.Analyzer {
internal sealed class PythonAnalyzerSession {
private readonly int _maxTaskRunning = Environment.ProcessorCount;
private readonly object _syncObj = new object();
private readonly Action<Task> _startNextSession;

private readonly IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> _walker;
private readonly PythonAnalyzerEntry _entry;
private readonly CancellationTokenSource _cts;
private readonly Action<Task> _startNextSession;
private readonly IServiceManager _services;
private readonly AsyncManualResetEvent _analysisCompleteEvent;
private readonly IDiagnosticsService _diagnosticsService;
private readonly IProgressReporter _progress;
private readonly IPythonAnalyzer _analyzer;
private readonly ILogger _log;

private State _state = State.NotStarted;
private IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> _walker;
private State _state;
private bool _isCanceled;
private int _runningTasks;
private int _version;
private PythonAnalyzerSession _nextSession;

public bool IsCompleted {
get {
Expand All @@ -58,21 +56,25 @@ public bool IsCompleted {
}
}

public int Version => _version;
public int Version { get; }

public PythonAnalyzerSession(IServiceManager services,
IProgressReporter progress,
AsyncManualResetEvent analysisCompleteEvent,
Action<Task> startNextSession,
CancellationToken analyzerToken,
CancellationToken sessionToken,
IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> walker,
int version) {
int version,
PythonAnalyzerEntry entry) {

_services = services;
_analysisCompleteEvent = analysisCompleteEvent;
_startNextSession = StartNextSession;
_version = version;
_startNextSession = startNextSession;
Version = version;
_walker = walker;
_entry = entry;
_state = State.NotStarted;
_cts = CancellationTokenSource.CreateLinkedTokenSource(analyzerToken, sessionToken);

_diagnosticsService = _services.GetService<IDiagnosticsService>();
Expand All @@ -81,119 +83,64 @@ public PythonAnalyzerSession(IServiceManager services,
_log = _services.GetService<ILogger>();
}

public void Start(PythonAnalyzerSession previousSession, PythonAnalyzerEntry entry) {
IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> walker;
State previousSessionState;

public void Start(bool analyzeEntry) {
lock (_syncObj) {
walker = _walker;
if (_state != State.NotStarted) {
_cts.Dispose();
analyzeEntry = false;
} else if (_state == State.Completed) {
return;
}

previousSessionState = previousSession?.CancelOrSchedule(this, _version) ?? State.Completed;
if (previousSessionState == State.Completed) {
} else {
_state = State.Started;
_walker = null;
}
}

switch (previousSessionState) {
case State.Started when entry.IsUserModule:
StartAnalysis(entry, walker.Version);
break;
case State.Completed:
Start(walker);
break;
if (analyzeEntry && _entry != null) {
Task.Run(() => Analyze(_entry, _walker.Version, _cts.Token), _cts.Token).DoNotWait();
} else {
StartAsync(_walker).ContinueWith(_startNextSession).DoNotWait();
}
}

private void StartNextSession(Task task) {
PythonAnalyzerSession nextSession;
public void Cancel() {
lock (_syncObj) {
_walker = null;
nextSession = _nextSession;
_nextSession = null;
_isCanceled = true;
}

nextSession?.TryStart();
}

private State CancelOrSchedule(PythonAnalyzerSession nextSession, int version) {
lock (_syncObj) {
Check.InvalidOperation(_nextSession == null);
Check.InvalidOperation(nextSession != null);
switch (_state) {
case State.NotStarted:
_state = State.Completed;
break;
case State.Started:
_nextSession = nextSession;
Interlocked.Exchange(ref _version, version);
break;
case State.Completed:
break;
default:
throw new ArgumentOutOfRangeException();
}

return _state;
}
}

private void TryStart() {
IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> walker = default;
lock (_syncObj) {
if (_state == State.NotStarted) {
_state = State.Started;
walker = _walker;
}

_walker = null;
}

if (walker != default) {
Start(walker);
}
}

private void Start(IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> walker) => StartAsync(walker).ContinueWith(_startNextSession).DoNotWait();

private async Task StartAsync(IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEntry> walker) {
int version;
lock (_syncObj) {
version = _version;
var notAnalyzed = walker.AffectedValues.Count(e => e.NotAnalyzed);

if (version > walker.Version && notAnalyzed < _maxTaskRunning) {
if (_isCanceled && notAnalyzed < _maxTaskRunning) {
_state = State.Completed;
_cts.Dispose();
return;
}
}


var cancellationToken = _cts.Token;
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Contributor Author

@AlexanderSher AlexanderSher Apr 2, 2019

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Fixes ODE in:

Unhandled Exception: System.ObjectDisposedException: The CancellationTokenSource has been disposed.
 at System.Threading.CancellationTokenSource.ThrowObjectDisposedException()
 at System.Threading.CancellationTokenSource.get_Token()
 at Microsoft.Python.Analysis.Analyzer.PythonAnalyzerSession.<>c__DisplayClass29_0.<StartAnalysis>b__0() in F:\PLS\src\Analysis\Ast\Impl\Analyzer\PythonAnalyzerSession.cs:line 280
 at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
 at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot)
--- End of stack trace from previous location where exception was thrown ---
 at Microsoft.Python.Core.TaskExtensions.<>c.<DoNotWaitThreadContinuation>b__4_0(Object s) in F:\PLS\src\Core\Impl\Extensions\TaskExtensions.cs:line 79
 at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
 at System.Threading.ThreadPoolWorkQueue.Dispatch()

var stopWatch = Stopwatch.StartNew();
foreach (var affectedEntry in walker.AffectedValues) {
affectedEntry.Invalidate(version);
affectedEntry.Invalidate(Version);
}

var originalRemaining = walker.Remaining;
var remaining = originalRemaining;
try {
_log?.Log(TraceEventType.Verbose, $"Analysis version {walker.Version} of {originalRemaining} entries has started.");
remaining = await AnalyzeAffectedEntriesAsync(walker, stopWatch, _cts.Token);
remaining = await AnalyzeAffectedEntriesAsync(walker, stopWatch, cancellationToken);
} finally {
_cts.Dispose();
stopWatch.Stop();

bool isCanceled;
lock (_syncObj) {
if (_version == walker.Version) {
_progress.ReportRemaining(walker.Remaining);
}

isCanceled = _isCanceled;
_state = State.Completed;
_cts.Dispose();
}

if (!isCanceled) {
_progress.ReportRemaining(walker.Remaining);
}

if (_log != null) {
Expand All @@ -212,7 +159,12 @@ private async Task<int> AnalyzeAffectedEntriesAsync(IDependencyChainWalker<Analy
IDependencyChainNode<PythonAnalyzerEntry> node;
var remaining = 0;
while ((node = await walker.GetNextAsync(cancellationToken)) != null) {
if (_version > walker.Version && !node.Value.NotAnalyzed) {
bool isCanceled;
lock (_syncObj) {
isCanceled = _isCanceled;
}

if (isCanceled && !node.Value.NotAnalyzed) {
remaining++;
node.Skip();
continue;
Expand All @@ -227,7 +179,12 @@ private async Task<int> AnalyzeAffectedEntriesAsync(IDependencyChainWalker<Analy

if (walker.MissingKeys.All(k => k.IsTypeshed)) {
Interlocked.Exchange(ref _runningTasks, 0);
if (_version == walker.Version) {
bool isCanceled;
lock (_syncObj) {
isCanceled = _isCanceled;
}

if (!isCanceled) {
_analysisCompleteEvent.Set();
}
}
Expand Down Expand Up @@ -269,16 +226,18 @@ private void Analyze(IDependencyChainWalker<AnalysisModuleKey, PythonAnalyzerEnt
node.Commit();
_log?.Log(TraceEventType.Verbose, $"Analysis of {module.Name}({module.ModuleType}) failed.");
} finally {
if (_version == walker.Version) {
bool isCanceled;
lock (_syncObj) {
isCanceled = _isCanceled;
}

if (!isCanceled) {
_progress.ReportRemaining(walker.Remaining);
}
Interlocked.Decrement(ref _runningTasks);
}
}

private void StartAnalysis(PythonAnalyzerEntry entry, int version)
=> Task.Run(() => Analyze(entry, version, _cts.Token), _cts.Token).DoNotWait();

private void Analyze(PythonAnalyzerEntry entry, int version, CancellationToken cancellationToken) {
var stopWatch = Stopwatch.StartNew();
try {
Expand Down