Joseph Doherty
f7ca2c5826
The soft deadline T was armed on the host at submit, so the pipe round trip
and the time a starved worker waits to be scheduled counted against the
script: under load a trivial script reported 'script timed out', in Shadow
mode that was a script mismatch, and at T + G the host killed the worker and
struck the key.
- Protocol (additive, negotiated): Hello/Ready.worker_soft_clock and
EvalResults.soft_expired_eval_ids. protocol_version stays 1; a worker that
does not echo the flag keeps the pre-#827 host clock.
- Worker: the watchdog runs each run's soft clock from the moment an
evaluation thread starts it and reports the crossing (woken early for
budgets shorter than its 50 ms poll). It still never cancels by itself;
its fail-fast is anchored at the soft notice + G + margin.
- Host (PendingEval): the soft notice answers the caller and arms the kill G
later. The host's own timer becomes a transport deadline, T + G from submit
(restarted at a deferred run's start); passing it with no result and no
notice yields TransportTimedOut -> Unavailable 'script worker unresponsive'
(BadResourceUnavailable, recovery = the run's completion), no strike, no
kill, no Cancel. A re-trigger refused by that still-unanswered run is
Unavailable too, not 'previous run still running'. Counted as
otopcua.script.ipc.timeouts{kind}.
- Frame writer: coalescing now carries soft_expired_eval_ids (it silently
dropped them); the host processes soft notices before results in a frame.
- Shadow: unresponsive is shadow_unavailable (Unavailable), never a mismatch.
Tests: WorkerSoftClockTests suspends the real worker (SIGSTOP via libc kill /
NtSuspendProcess) - a stall past T still returns 7; a stall past T + G is a
runner fault with nothing struck; a late-starting runaway is still timed out
at T from its start and killed G after; Shadow stays match /
shadow_unavailable; both clocks enforce T and G; PendingEval state machine.
340 lines
18 KiB
C#
340 lines
18 KiB
C#
using System.Diagnostics;
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using System.Runtime.InteropServices;
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using System.Security.Cryptography;
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using System.Text;
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using Serilog;
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using Shouldly;
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using Xunit;
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using ZB.MOM.WW.OtOpcUa.Core.Scripting;
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using ZB.MOM.WW.OtOpcUa.Core.Scripting.OutOfProcess;
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using ZB.MOM.WW.OtOpcUa.Core.Scripting.Protocol.V1;
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namespace ZB.MOM.WW.OtOpcUa.ScriptWorker.Tests;
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/// <summary>
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/// lmxopcua#827: the soft deadline T measures the script's OWN execution — the worker runs it from the moment an
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/// evaluation thread starts the run — so the pipe round trip and the time a starved worker waits to be scheduled
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/// no longer count against the script. The host keeps a transport deadline (T + G from submit) and reports passing
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/// it as a runner fault (<see cref="ScriptRunOutcome.WorkerUnresponsiveReason"/>, BadResourceUnavailable), never as a
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/// script timeout. The starved worker is made real here: its process is suspended (SIGSTOP / NtSuspendProcess)
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/// while a trivial script is submitted.
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/// </summary>
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[Collection(ScriptWorkerCollection.Name)]
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[Trait("Category", "ScriptWorker")]
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public sealed class WorkerSoftClockTests
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{
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private const string Trivial = "return 7;";
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private const string Runaway = "while (true) { }";
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private static CancellationToken Ct => TestContext.Current.CancellationToken;
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/// <summary>
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/// A runner whose worker heartbeats every 2 s, so the host's silence kill (3 intervals) stays well clear of the
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/// suspensions below: what is measured is the deadline, not the heartbeat monitor.
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/// </summary>
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private static OutOfProcessScriptRunner Runner(TimeSpan hardGrace, ILogger? log = null)
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=> new(Scripts.Options(hardGrace: hardGrace, quarantineAfterKills: 1), log ?? new LoggerConfiguration().CreateLogger(), null,
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heartbeatInterval: TimeSpan.FromSeconds(2), loadTimeout: TimeSpan.FromSeconds(60));
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private static async Task<WorkerConnection> WarmAsync(OutOfProcessScriptRunner runner, string key)
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{
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var warm = await runner.RunAsync(Scripts.Vt(key, Trivial, TimeSpan.FromSeconds(30)), Ct);
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warm.Status.ShouldBe(ScriptRunStatus.Ok, warm.Reason);
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var worker = runner.Shards[0].Current.ShouldNotBeNull();
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worker.WorkerSoftClock.ShouldBeTrue("the worker negotiated the soft clock");
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return worker;
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}
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/// <summary>
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/// The issue's headline: a worker that cannot be scheduled for longer than T, but shorter than the transport
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/// deadline, answers a trivial script with its value. Before #827 the host's clock, started at submit, answered
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/// <c>script timed out after 0.3s</c> for <c>return 7;</c>.
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/// </summary>
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[Fact]
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public async Task A_worker_stalled_for_longer_than_T_still_answers_a_trivial_script_with_its_value()
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{
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var softT = TimeSpan.FromMilliseconds(300);
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await using var runner = Runner(hardGrace: TimeSpan.FromSeconds(3));
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var worker = await WarmAsync(runner, "trivial");
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Task<ScriptRunOutcome> run;
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using (ProcessFreezer.Freeze(worker.Pid))
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{
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run = runner.RunAsync(Scripts.Vt("trivial", Trivial, softT), Ct);
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await Task.Delay(softT * 4, Ct); // 1.2 s: well past T on the host's clock
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run.IsCompleted.ShouldBeFalse("nothing can answer while the worker is suspended");
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}
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var outcome = await run.WaitAsync(TimeSpan.FromSeconds(30), Ct);
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outcome.Status.ShouldBe(ScriptRunStatus.Ok, outcome.Reason);
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outcome.Value.ShouldBe(7);
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runner.Shards[0].Current.ShouldNotBeNull().Pid.ShouldBe(worker.Pid, "a stall is not a deadline kill");
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runner.QuarantinedKeys(ScriptContextKind.VirtualTag).ShouldBeEmpty();
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}
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/// <summary>
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/// A stall past the transport deadline (T + G) is the runner's fault: the caller gets
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/// <see cref="ScriptRunOutcome.WorkerUnresponsiveReason"/> as <see cref="ScriptRunStatus.Unavailable"/> (published
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/// BadResourceUnavailable) with a recovery that completes when the worker answers; a re-trigger meanwhile is the
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/// runner's fault too (not "previous run still running"); the worker is not killed and the key is not struck.
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/// Before #827 this was a script timeout at T and a deadline kill at T + G that struck the key — with
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/// QuarantineAfterKills = 1, a quarantine for <c>return 7;</c>.
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/// </summary>
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[Fact]
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public async Task A_worker_stalled_past_the_transport_deadline_is_a_runner_fault_and_nothing_is_struck()
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{
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var softT = TimeSpan.FromMilliseconds(200);
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var grace = TimeSpan.FromMilliseconds(400);
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await using var runner = Runner(grace);
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var worker = await WarmAsync(runner, "trivial");
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ScriptRunOutcome stalled, retriggered;
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using (ProcessFreezer.Freeze(worker.Pid))
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{
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stalled = await runner.RunAsync(Scripts.Vt("trivial", Trivial, softT), Ct).WaitAsync(TimeSpan.FromSeconds(10), Ct);
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retriggered = await runner.RunAsync(Scripts.Vt("trivial", Trivial, softT), Ct).WaitAsync(TimeSpan.FromSeconds(10), Ct);
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stalled.Recovery.ShouldNotBeNull().IsCompleted.ShouldBeFalse("the worker has not answered yet");
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}
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stalled.Status.ShouldBe(ScriptRunStatus.Unavailable, stalled.Reason);
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stalled.Reason.ShouldBe(ScriptRunOutcome.WorkerUnresponsiveReason);
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retriggered.Status.ShouldBe(ScriptRunStatus.Unavailable, retriggered.Reason);
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retriggered.Reason.ShouldBe(ScriptRunOutcome.WorkerUnresponsiveReason);
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stalled.ToVirtualTagEvalResult().StatusCode.ShouldBe(Commons.OpcUa.OpcUaStatus.BadResourceUnavailable);
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await stalled.Recovery!.WaitAsync(TimeSpan.FromSeconds(30), Ct);
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var next = await runner.RunAsync(Scripts.Vt("trivial", Trivial, softT), Ct);
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next.Status.ShouldBe(ScriptRunStatus.Ok, next.Reason);
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next.Value.ShouldBe(7);
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runner.Shards[0].Current.ShouldNotBeNull().Pid.ShouldBe(worker.Pid, "a stall is not a deadline kill");
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runner.QuarantinedKeys(ScriptContextKind.VirtualTag).ShouldBeEmpty();
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}
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/// <summary>
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/// The other side of the contract is unchanged: a script that really runs past T is answered at T from its own
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/// start and killed G after that, even with the worker stalled before it started. Positive control for the two
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/// tests above — they would also pass if the runner simply never timed anything out.
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/// </summary>
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[Fact]
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public async Task A_runaway_that_starts_late_is_still_timed_out_at_T_from_its_start_and_killed_at_G()
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{
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var softT = TimeSpan.FromMilliseconds(300);
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var grace = TimeSpan.FromMilliseconds(600);
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var stall = TimeSpan.FromMilliseconds(500);
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await using var runner = Runner(grace);
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var worker = await WarmAsync(runner, "warm");
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var load = await runner.RunAsync(Scripts.Vt("runaway", "return 0;", TimeSpan.FromSeconds(30)), Ct);
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load.Status.ShouldBe(ScriptRunStatus.Ok, load.Reason);
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var sw = Stopwatch.StartNew();
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Task<ScriptRunOutcome> run;
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using (ProcessFreezer.Freeze(worker.Pid))
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{
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run = runner.RunAsync(Scripts.Vt("runaway", Runaway, softT), Ct);
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await Task.Delay(stall, Ct);
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}
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var thawed = sw.Elapsed;
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var outcome = await run.WaitAsync(TimeSpan.FromSeconds(30), Ct);
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var answered = sw.Elapsed;
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outcome.Status.ShouldBe(ScriptRunStatus.Failed);
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outcome.Reason.ShouldNotBeNull().ShouldStartWith("script timed out after ");
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(answered - thawed).ShouldBeGreaterThanOrEqualTo(softT - TimeSpan.FromMilliseconds(50), "T counts from the run's start, after the stall");
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var exit = await worker.Exited.WaitAsync(TimeSpan.FromSeconds(30), Ct);
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exit.Reason.ShouldBe(WorkerExitReason.KilledDeadline);
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exit.CulpritKey.ShouldBe(InProcessScriptRunner.ScopedKey(ScriptContextKind.VirtualTag, "runaway"));
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(sw.Elapsed - thawed).ShouldBeGreaterThanOrEqualTo(softT + grace - TimeSpan.FromMilliseconds(50), "G counts from the soft deadline");
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}
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/// <summary>
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/// Shadow (lmxopcua#780 P2) compares the shadow pool with the published in-process result; a starved worker used to
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/// show up there as a script mismatch (published Ok, shadow "timed out") and skew the census for the OutOfProcess
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/// flip. Now a stall shorter than the transport deadline is a match, and a longer one is <c>shadow_unavailable</c>
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/// — never a mismatch — including the re-trigger that finds the stalled run still holding its slot.
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/// </summary>
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[Fact]
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public async Task In_Shadow_a_stalled_worker_is_a_match_or_shadow_unavailable_never_a_mismatch()
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{
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var softT = TimeSpan.FromMilliseconds(300);
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var grace = TimeSpan.FromSeconds(1);
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var options = Scripts.Options(hardGrace: grace, quarantineAfterKills: 1);
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options.Runner = ScriptRunnerMode.Shadow;
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await using var pool = Runner(grace);
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using var shadow = new ShadowScriptRunner(pool, options, new LoggerConfiguration().CreateLogger());
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var worker = await WarmAsync(pool, "trivial");
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var published = ScriptRunOutcome.Ok(7);
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// Stall past T, short of T + G: compared, and a match.
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using (ProcessFreezer.Freeze(worker.Pid))
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{
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shadow.Mirror(Scripts.Vt("trivial", Trivial, softT), published);
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await Task.Delay(TimeSpan.FromMilliseconds(900), Ct);
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}
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(await shadow.WaitIdleAsync(TimeSpan.FromSeconds(30))).ShouldBeTrue();
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shadow.Stats().Matched.ShouldBe(1, Summary(shadow));
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// Stall past T + G: not compared. The second mirror arrives while the first still holds the key's slot.
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using (ProcessFreezer.Freeze(worker.Pid))
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{
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shadow.Mirror(Scripts.Vt("trivial", Trivial, softT), published);
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await Scripts.Eventually(() => shadow.Stats().ShadowUnavailable == 1, TimeSpan.FromSeconds(10), "the transport deadline");
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shadow.Mirror(Scripts.Vt("trivial", Trivial, softT), published);
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await Scripts.Eventually(() => shadow.Stats().ShadowUnavailable == 2, TimeSpan.FromSeconds(10), "the stalled re-trigger");
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}
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(await shadow.WaitIdleAsync(TimeSpan.FromSeconds(30))).ShouldBeTrue();
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var stats = shadow.Stats();
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stats.Mismatched.ShouldBe(0, Summary(shadow));
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stats.ShadowUnavailable.ShouldBe(2, Summary(shadow));
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stats.Matched.ShouldBe(1);
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pool.Shards[0].Current.ShouldNotBeNull().Pid.ShouldBe(worker.Pid);
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}
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/// <summary>
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/// Protocol compatibility: the soft clock is negotiated (<c>Hello.worker_soft_clock</c> → <c>Ready.worker_soft_clock</c>).
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/// A host that does not ask for it keeps the pre-#827 contract — the soft deadline is the host's, from submit,
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/// and the worker sends no soft notices — and a runaway is still answered at T and killed at T + G.
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/// </summary>
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[Theory]
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[InlineData(true)]
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[InlineData(false)]
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public async Task The_soft_clock_is_negotiated_and_both_clocks_enforce_T_and_G(bool workerSoftClock)
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{
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var spec = new WorkerLaunchSpec("t", OutOfProcessScriptRunner.ResolveWorkerPath(new ScriptWorkerOptions { ExecutablePath = Scripts.WorkerUnderTest }),
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256L * 1024 * 1024, EvalThreads: 2, HardGrace: TimeSpan.FromSeconds(1), HeartbeatInterval: TimeSpan.FromSeconds(1),
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HandshakeTimeout: TimeSpan.FromSeconds(15), WorkerSoftClock: workerSoftClock);
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var connection = await WorkerConnection.StartAsync(spec, new LoggerConfiguration().CreateLogger(), _ => { }, _ => { }, Ct);
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await using var _ = connection;
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connection.WorkerSoftClock.ShouldBe(workerSoftClock);
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var entry = await connection.EnsureLoadedAsync("k", ContextKind.VirtualTag, Runaway,
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SHA256.HashData(Encoding.UTF8.GetBytes(Runaway)), []).WaitAsync(TimeSpan.FromSeconds(60), Ct);
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entry.Outcome.ShouldNotBeNull().Ok.ShouldBeTrue();
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var softT = TimeSpan.FromMilliseconds(300);
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var grace = TimeSpan.FromMilliseconds(500);
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var sw = Stopwatch.StartNew();
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var pending = connection.Submit("k",
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new EvalRequest { Key = "k", SoftTimeoutMs = (uint)softT.TotalMilliseconds, HardGraceMs = (uint)grace.TotalMilliseconds, NowUtcTicks = DateTime.UtcNow.Ticks },
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softT, grace, null);
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(await pending.Outcome.WaitAsync(TimeSpan.FromSeconds(10), Ct)).ShouldBeSameAs(PendingEval.SoftTimedOut);
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sw.Elapsed.ShouldBeGreaterThanOrEqualTo(softT - TimeSpan.FromMilliseconds(20));
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connection.Cancel(pending);
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var exit = await connection.Exited.WaitAsync(TimeSpan.FromSeconds(10), Ct);
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exit.Reason.ShouldBe(WorkerExitReason.KilledDeadline);
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sw.Elapsed.ShouldBeGreaterThanOrEqualTo(softT + grace - TimeSpan.FromMilliseconds(50));
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}
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// ---------------------------------------------------------------- PendingEval, no process
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/// <summary>The host side of the worker clock, deterministic: no notice means the transport deadline at T + G.</summary>
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[Fact]
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public async Task Worker_clock_with_no_word_from_the_worker_answers_transport_timed_out_at_T_plus_G_and_never_kills()
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{
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var killed = 0;
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var pending = new PendingEval("k", 1);
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var sw = Stopwatch.StartNew();
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pending.Arm(TimeSpan.FromMilliseconds(100), TimeSpan.FromMilliseconds(200), _ => Interlocked.Increment(ref killed), workerClock: true);
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(await pending.Outcome.WaitAsync(TimeSpan.FromSeconds(10), Ct)).ShouldBeSameAs(PendingEval.TransportTimedOut);
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sw.Elapsed.ShouldBeGreaterThanOrEqualTo(TimeSpan.FromMilliseconds(280));
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await Task.Delay(500, Ct);
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killed.ShouldBe(0, "a late worker is not the script's fault");
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// A soft notice after the transport answer still arms the kill: the script itself ran for T.
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pending.SoftExpired();
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await Scripts.Eventually(() => Volatile.Read(ref killed) == 1, TimeSpan.FromSeconds(10), "the kill G after the soft notice");
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}
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/// <summary>The soft notice answers the caller and arms the kill G later; a result before then cancels it.</summary>
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[Fact]
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public async Task Worker_clock_soft_notice_answers_soft_timed_out_and_arms_the_kill_G_later()
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{
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var killed = 0;
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var pending = new PendingEval("k", 1);
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pending.Arm(TimeSpan.FromSeconds(30), TimeSpan.FromMilliseconds(300), _ => Interlocked.Increment(ref killed), workerClock: true);
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pending.Outcome.IsCompleted.ShouldBeFalse();
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var sw = Stopwatch.StartNew();
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pending.SoftExpired();
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(await pending.Outcome.WaitAsync(TimeSpan.FromSeconds(1), Ct)).ShouldBeSameAs(PendingEval.SoftTimedOut);
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await Scripts.Eventually(() => Volatile.Read(ref killed) == 1, TimeSpan.FromSeconds(10), "the kill");
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sw.Elapsed.ShouldBeGreaterThanOrEqualTo(TimeSpan.FromMilliseconds(280));
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var answered = new PendingEval("k2", 2);
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answered.Arm(TimeSpan.FromSeconds(30), TimeSpan.FromMilliseconds(100), _ => Interlocked.Increment(ref killed), workerClock: true);
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answered.SoftExpired();
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answered.Complete(new EvalResult { EvalId = 2 });
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await Task.Delay(400, Ct);
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killed.ShouldBe(1, "a run that answered inside G is not killed");
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}
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/// <summary>Under the host clock a soft notice means nothing (a worker that did not negotiate it cannot send one).</summary>
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[Fact]
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public void Host_clock_ignores_a_soft_notice()
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{
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var pending = new PendingEval("k", 1);
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pending.Arm(TimeSpan.FromSeconds(30), TimeSpan.FromSeconds(30), _ => { }, workerClock: false);
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pending.SoftExpired();
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pending.Outcome.IsCompleted.ShouldBeFalse();
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pending.Complete(null);
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}
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private static string Summary(ShadowScriptRunner shadow)
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=> $"{shadow.Stats()}; " + string.Join("; ", shadow.Mismatches.Select(m => $"{m.Key}: {m.LastReason} — {m.LastSummary}"));
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}
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/// <summary>Suspends a process (SIGSTOP, or NtSuspendProcess on Windows) until disposed.</summary>
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internal sealed class ProcessFreezer : IDisposable
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{
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private readonly int _pid;
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private int _thawed;
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private ProcessFreezer(int pid)
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{
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_pid = pid;
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Signal(pid, stop: true);
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}
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public static ProcessFreezer Freeze(int pid) => new(pid);
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public void Dispose()
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{
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if (Interlocked.Exchange(ref _thawed, 1) == 0) Signal(_pid, stop: false);
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}
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private static void Signal(int pid, bool stop)
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{
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if (OperatingSystem.IsWindows())
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{
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using var process = Process.GetProcessById(pid);
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var status = stop ? NtSuspendProcess(process.Handle) : NtResumeProcess(process.Handle);
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status.ShouldBe(0, $"Nt{(stop ? "Suspend" : "Resume")}Process");
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return;
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}
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// libc kill(2), not the kill(1) command: a child process's exit is observed through the same SIGCHLD
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// handling that the suspended worker (another child of this process) just disturbed, and WaitForExit was
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// seen to take seconds.
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var signal = stop ? SigStop : SigCont;
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Kill(pid, signal).ShouldBe(0, $"kill({pid}, {signal}): errno {Marshal.GetLastPInvokeError()}");
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}
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/// <summary>SIGSTOP / SIGCONT: 17 / 19 on macOS (BSD), 19 / 18 on Linux.</summary>
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private static int SigStop => OperatingSystem.IsMacOS() ? 17 : 19;
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private static int SigCont => OperatingSystem.IsMacOS() ? 19 : 18;
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#pragma warning disable SYSLIB1054 // DllImport kept: LibraryImport would need AllowUnsafeBlocks for three test-only calls.
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[DllImport("libc", EntryPoint = "kill", SetLastError = true)]
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private static extern int Kill(int pid, int signal);
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[DllImport("ntdll.dll")]
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private static extern int NtSuspendProcess(IntPtr processHandle);
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[DllImport("ntdll.dll")]
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private static extern int NtResumeProcess(IntPtr processHandle);
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#pragma warning restore SYSLIB1054
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}
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