github/copilot-sdk · error · IllegalStateException

Interrupted while starting in-process runtime host.

Error message

Interrupted while starting in-process runtime host.

What it means

runHostStartOnBlockingThread submits the native hostStart call to a single-use executor and blocks on future.get(). If the calling thread is interrupted while waiting, the library restores the interrupt flag and throws IllegalStateException.

Solutions

1. Avoid interrupting threads performing FFI startup; use a dedicated startup thread not subject to cancellation.
2. Increase startup timeouts so watchdogs don't interrupt mid-start.
3. Retry initialization on a fresh (non-interrupted) thread with a new FfiRuntimeHost.
4. Catch IllegalStateException, check Thread.interrupted(), and handle shutdown gracefully.

Example fix

// before
executor.submit(() -> client.start(e, o)).cancel(true); // interrupts mid-FFI
// after
initFuture = CompletableFuture.runAsync(() -> client.start(e, o), initExecutor);
// don't cancel(true) during native start; await completion

if (Thread.currentThread().isInterrupted()) { /* defer init to a fresh thread */ }

try { host.start(e, o); } catch (IllegalStateException ex) { if (ex.getCause() instanceof InterruptedException || Thread.interrupted()) { /* reschedule init on new thread */ } else throw ex; }

When it happens

Trigger: Thread.interrupt() delivered to the thread blocked in start()/runHostStartOnBlockingThread — e.g. task cancellation, executor shutdown, or application shutdown interrupting worker threads.

Common situations: Cancelling a FutureTask/CompletableFuture wrapping client init; servlet container interrupting a slow request thread; test framework timeouts interrupting the test thread during slow native startup.

Understand the failure class

Background: Request timed out: what client-side request timeouts mean across libraries (Request timed out, TIMED_OUT, APITimeoutError) — this error's family across 39 libraries.

Related errors

• FfiRuntimeHost was closed during startup.
• Interrupted while waiting for callback data
• FfiRuntimeHost has already been started.
• copilot_runtime_host_start failed (library '').
• copilot_runtime_connection_open failed.

AI-assisted analysis of github/copilot-sdk@cd8cf15dc3 (2026-09-09). Data as JSON: /api/errors/a57493f843bb4b84. Report an issue: GitHub.

Appendix: source

Thrown at java/sdk/src/main/java/com/github/copilot/ffi/FfiRuntimeHost.java:253

                    synchronized (callbackDrainMonitor) {
                        callbackDrainMonitor.notifyAll();
                    }
                }
            }
        };
    }

    private int runHostStartOnBlockingThread(byte[] argvJson, byte[] envJson) {
        ReaderThreadFactory readerThreadFactory = new ReaderThreadFactory();
        ExecutorService executor = Executors
                .newSingleThreadExecutor(runnable -> readerThreadFactory.create(runnable, "copilot-ffi-host-start"));
        try {
            Future<Integer> future = executor.submit(() -> nativeBinding.hostStart(argvJson, argvJson.length, envJson,
                    envJson == null ? 0 : envJson.length));
            return future.get();
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new IllegalStateException("Interrupted while starting in-process runtime host.", e);
        } catch (ExecutionException e) {
            Throwable cause = e.getCause();
            if (cause instanceof RuntimeException runtimeException) {
                throw runtimeException;
            }
            throw new IllegalStateException("Failed to start in-process runtime host.", cause);
        } finally {
            executor.shutdownNow();
            try {
                executor.awaitTermination(5, TimeUnit.SECONDS);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }
    }

    private static byte[] buildArgvJson(String entrypointPath, CopilotClientOptions options) {
        List<String> argv = new ArrayList<>();

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