Skip to content

fix(middleware): avoid event-loop blocking in WorkspaceContextMiddleware onSystemPrompt #2632

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
zouyx merged 6 commits into from
Aug 12, 2026
+51 −8
Merged

fix(middleware): avoid event-loop blocking in WorkspaceContextMiddleware onSystemPrompt #2632

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
6 commits
Select commit Hold shift + click to select a range
9c31ea6
fix(middleware): avoid event-loop blocking in WorkspaceContextMiddlew…
rudy2steiner Aug 8, 2026
b320802
Merge branch 'main' into none_blocking
rudy2steiner Aug 9, 2026
f1c544d
Potential fix for pull request finding
zouyx Aug 9, 2026
1482a1e
Merge branch 'main' into none_blocking
rudy2steiner Aug 11, 2026
f9e4ca4
fix(test): coverage issue
rudy2steiner Aug 11, 2026
3dacad1
Merge branch 'main' into none_blocking
rudy2steiner Aug 12, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
18 changes: 10 additions & 8 deletions ...ness/src/main/java/io/agentscope/harness/agent/middleware/WorkspaceContextMiddleware.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@
import java.util.List;
import java.util.stream.Collectors;
import reactor.core.publisher.Mono;
import reactor.core.scheduler.Schedulers;

/**
* Appends workspace context (session info, AGENTS.md, MEMORY.md, knowledge) to the
Expand Down Expand Up @@ -181,14 +182,15 @@ public boolean isDisableMemoryHooks() {

@Override
public Mono<String> onSystemPrompt(Agent agent, RuntimeContext ctx, String currentPrompt) {
RuntimeContext rc = ctx != null ? ctx : RuntimeContext.empty();
String section = buildWorkspaceSection(rc);
if (section.isEmpty()) {
return Mono.just(currentPrompt);
}
String base = currentPrompt != null ? currentPrompt : "";
String separator = base.isEmpty() || base.endsWith("\n") ? "" : "\n";
return Mono.just(base + separator + section);
return Mono.fromCallable(
() -> {

@AgentScopeJavaBot AgentScopeJavaBot Aug 12, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[minor] Removed empty-section early-return guard. The original code had if (section.isEmpty()) return Mono.just(currentPrompt) which short-circuited when no workspace files existed. The new code always concatenates the section (even if empty), which may append an unnecessary trailing newline. Consider restoring the isEmpty guard inside the callable.

@AgentScopeJavaBot AgentScopeJavaBot Aug 12, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[minor] Removed empty-section early-return guard. The original code had if (section.isEmpty()) return Mono.just(currentPrompt) which short-circuited when no workspace files existed. The new code always concatenates the section (even if empty), which may append an unnecessary trailing newline. Consider restoring the isEmpty guard inside the callable.

RuntimeContext rc = ctx != null ? ctx : RuntimeContext.empty();
String base = currentPrompt != null ? currentPrompt : "";
String section = buildWorkspaceSection(rc);
String separator = base.isEmpty() || base.endsWith("\n") ? "" : "\n";
return base + separator + section;
})
.subscribeOn(Schedulers.boundedElastic());
}

@AgentScopeJavaBot AgentScopeJavaBot Aug 12, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[major] Missing onErrorResume for graceful degradation. buildWorkspaceSection() performs multiple filesystem reads. If any throws, the Mono.fromCallable will propagate the error through the middleware chain, failing the entire agent call. For a supplementary-context middleware, this is overly aggressive. Consider adding .onErrorResume(e -> { log.warn(...); return Mono.just(currentPrompt); }) after subscribeOn to degrade gracefully.

@AgentScopeJavaBot AgentScopeJavaBot Aug 12, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[major] Missing onErrorResume for graceful degradation. buildWorkspaceSection() performs multiple filesystem reads. If any throws, the Mono.fromCallable will propagate the error through the middleware chain, failing the entire agent call. For a supplementary-context middleware, this is overly aggressive. Consider adding .onErrorResume(e -> { log.warn(...); return Mono.just(currentPrompt); }) after subscribeOn to degrade gracefully.


private String buildWorkspaceSection(RuntimeContext rc) {
Expand Down
41 changes: 41 additions & 0 deletions ...va/io/agentscope/harness/agent/middleware/WorkspaceContextMiddlewareMemoryPromptTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@

import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNotSame;
import static org.junit.jupiter.api.Assertions.assertTrue;

import io.agentscope.core.agent.RuntimeContext;
Expand All @@ -25,6 +26,7 @@
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.io.TempDir;
Expand Down Expand Up @@ -52,6 +54,45 @@ private WorkspaceManager track(WorkspaceManager wm) {

@TempDir Path workspace;

@Test
void onSystemPromptBuildsWorkspaceContextOnBoundedElastic() {

@AgentScopeJavaBot AgentScopeJavaBot Aug 12, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[nitpick] The test assertion assertFalse(callerThread[0]) is somewhat fragile — it only checks that the caller thread differs from the current thread at assertion time. If the test happens to run on the bounded-elastic scheduler itself, the assertion would still pass but the intent (offloading to a different scheduler) would be better captured by checking the thread name contains 'boundedElastic'.

@AgentScopeJavaBot AgentScopeJavaBot Aug 12, 2026

Copy link
Copy Markdown
Collaborator

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

[nitpick] The test assertion assertFalse(callerThread[0]) is somewhat fragile — it only checks that the caller thread differs from the current thread at assertion time. If the test happens to run on the bounded-elastic scheduler itself, the assertion would still pass but the intent (offloading to a different scheduler) would be better captured by checking the thread name contains 'boundedElastic'.

Thread callerThread = Thread.currentThread();
AtomicReference<Thread> readThread = new AtomicReference<>();
WorkspaceManager wm =
track(
new WorkspaceManager(workspace) {
@Override
public String readAgentsMd(RuntimeContext rc) {
readThread.set(Thread.currentThread());
return "agent persona";
}
});
WorkspaceContextMiddleware mw = new WorkspaceContextMiddleware(wm);

String prompt = mw.onSystemPrompt(null, RuntimeContext.empty(), "BASE\n").block();

assertNotNull(prompt);
assertTrue(prompt.contains("agent persona"));
assertNotNull(readThread.get());
assertNotSame(
callerThread, readThread.get(), "workspace context read ran on caller thread");
}

@Test
void onSystemPromptHandlesNullAndNonNewlineBasePrompts() {
WorkspaceManager wm = track(new WorkspaceManager(workspace));
WorkspaceContextMiddleware mw = new WorkspaceContextMiddleware(wm);

String promptWithoutBase = mw.onSystemPrompt(null, null, null).block();
String promptWithBase = mw.onSystemPrompt(null, RuntimeContext.empty(), "BASE").block();

assertNotNull(promptWithoutBase);
assertFalse(promptWithoutBase.startsWith("null"));
assertTrue(promptWithoutBase.contains("## Domain Knowledge"));
assertNotNull(promptWithBase);
assertTrue(promptWithBase.startsWith("BASE\n"));
}

@Test
void defaultFlags_includeMemoryRecallPersistenceAndContext() throws Exception {
Files.writeString(workspace.resolve("MEMORY.md"), "remember: cats prefer windowsills");
Expand Down
Loading