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fix: Fix ADK Runner race condition for sequential tool execution #1138

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Merged
copybara-service merged 1 commit into from
Apr 14, 2026
+27 −184
Merged

fix: Fix ADK Runner race condition for sequential tool execution #1138

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25 changes: 4 additions & 21 deletions core/src/main/java/com/google/adk/flows/llmflows/BaseLlmFlow.java
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Original file line number Diff line number Diff line change
Expand Up @@ -461,31 +461,14 @@ public Flowable<Event> run(InvocationContext invocationContext) {

private Flowable<Event> run(
Context spanContext, InvocationContext invocationContext, int stepsCompleted) {
Flowable<Event> currentStepEvents = runOneStep(spanContext, invocationContext);

Flowable<Event> processedEvents =
currentStepEvents
.concatMap(
event ->
invocationContext
.sessionService()
.appendEvent(invocationContext.session(), event)
.flatMap(
registeredEvent ->
invocationContext
.pluginManager()
.onEventCallback(invocationContext, registeredEvent)
.defaultIfEmpty(registeredEvent))
.toFlowable())
.cache();

Flowable<Event> currentStepEvents = runOneStep(spanContext, invocationContext).cache();
if (stepsCompleted + 1 >= maxSteps) {
logger.debug("Ending flow execution because max steps reached.");
return processedEvents;
return currentStepEvents;
}

return processedEvents.concatWith(
processedEvents
return currentStepEvents.concatWith(
currentStepEvents
.toList()
.flatMapPublisher(
eventList -> {
Expand Down
25 changes: 8 additions & 17 deletions core/src/main/java/com/google/adk/flows/llmflows/Functions.java
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Original file line number Diff line number Diff line change
Expand Up @@ -71,10 +71,8 @@ public final class Functions {
private static final Logger logger = LoggerFactory.getLogger(Functions.class);

/** Generates a unique ID for a function call. */
public static String generateClientFunctionCallId(FunctionCall functionCall) {
String source =
functionCall.name().orElse("") + functionCall.args().orElse(ImmutableMap.of()).toString();
return AF_FUNCTION_CALL_ID_PREFIX + UUID.nameUUIDFromBytes(source.getBytes()).toString();
public static String generateClientFunctionCallId() {
return AF_FUNCTION_CALL_ID_PREFIX + UUID.randomUUID();
}

/**
Expand Down Expand Up @@ -103,7 +101,7 @@ public static void populateClientFunctionCallId(Event modelResponseEvent) {
FunctionCall functionCall = part.functionCall().get();
if (functionCall.id().isEmpty() || functionCall.id().get().isEmpty()) {
FunctionCall updatedFunctionCall =
functionCall.toBuilder().id(generateClientFunctionCallId(functionCall)).build();
functionCall.toBuilder().id(generateClientFunctionCallId()).build();
newParts.add(part.toBuilder().functionCall(updatedFunctionCall).build());
modified = true;
} else {
Expand Down Expand Up @@ -623,7 +621,7 @@ private static Event buildResponseEvent(
.build();

return Event.builder()
.id(toolContext.functionCallId().orElseGet(Event::generateEventId))
.id(Event.generateEventId())
.invocationId(invocationContext.invocationId())
.author(invocationContext.agent().name())
.branch(invocationContext.branch().orElse(null))
Expand Down Expand Up @@ -659,17 +657,17 @@ public static Optional<Event> generateRequestConfirmationEvent(
.collect(toImmutableMap(Map.Entry::getKey, Map.Entry::getValue))
.entrySet()) {

FunctionCall.Builder builder =
FunctionCall requestConfirmationFunctionCall =
FunctionCall.builder()
.name(REQUEST_CONFIRMATION_FUNCTION_CALL_NAME)
.args(
ImmutableMap.of(
"originalFunctionCall",
functionCallsById.get(entry.getKey()),
"toolConfirmation",
entry.getValue()));
FunctionCall requestConfirmationFunctionCall =
builder.id(generateClientFunctionCallId(builder.build())).build();
entry.getValue()))
.id(generateClientFunctionCallId())
.build();

longRunningToolIds.add(requestConfirmationFunctionCall.id().get());
parts.add(Part.builder().functionCall(requestConfirmationFunctionCall).build());
Expand All @@ -682,15 +680,8 @@ public static Optional<Event> generateRequestConfirmationEvent(
var contentBuilder = Content.builder().parts(parts);
functionResponseEvent.content().flatMap(Content::role).ifPresent(contentBuilder::role);

String deterministicId =
"req-conf-"
+ functionResponseEvent.actions().requestedToolConfirmations().keySet().stream()
.sorted()
.collect(java.util.stream.Collectors.joining("-"));

return Optional.of(
Event.builder()
.id(deterministicId)
.invocationId(invocationContext.invocationId())
.author(invocationContext.agent().name())
.branch(invocationContext.branch().orElse(null))
Expand Down
38 changes: 13 additions & 25 deletions core/src/main/java/com/google/adk/runner/Runner.java
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Original file line number Diff line number Diff line change
Expand Up @@ -68,12 +68,9 @@
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.jspecify.annotations.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** The main class for the GenAI Agents runner. */
public class Runner {
private static final Logger logger = LoggerFactory.getLogger(Runner.class);
private final BaseAgent agent;
private final String appName;
private final BaseArtifactService artifactService;
Expand Down Expand Up @@ -573,28 +570,19 @@ private Flowable<Event> runAgentWithUpdatedSession(
.agent()
.runAsync(contextWithUpdatedSession)
.concatMap(
agentEvent -> {
// TODO: remove this hack after deprecating runAsync with Session.
copySessionStates(updatedSession, initialContext.session());

// TODO: b/502182243 - Investigate if appendEvent should be made idempotent in
// SessionService to avoid this check.
if (updatedSession.events().stream()
.anyMatch(e -> e.id() != null && e.id().equals(agentEvent.id()))) {
logger.debug("Event {} already in session, skipping append", agentEvent.id());
return io.reactivex.rxjava3.core.Flowable.just(agentEvent);
}
return this.sessionService
.appendEvent(updatedSession, agentEvent)
.flatMap(
registeredEvent -> {
return contextWithUpdatedSession
.pluginManager()
.onEventCallback(contextWithUpdatedSession, registeredEvent)
.defaultIfEmpty(registeredEvent);
})
.toFlowable();
});
agentEvent ->
this.sessionService
.appendEvent(updatedSession, agentEvent)
.flatMap(
registeredEvent -> {
// TODO: remove this hack after deprecating runAsync with Session.
copySessionStates(updatedSession, initialContext.session());
return contextWithUpdatedSession
.pluginManager()
.onEventCallback(contextWithUpdatedSession, registeredEvent)
.defaultIfEmpty(registeredEvent);
})
.toFlowable());

// If beforeRunCallback returns content, emit it and skip agent
Context capturedContext = Context.current();
Expand Down
123 changes: 2 additions & 121 deletions core/src/test/java/com/google/adk/runner/RunnerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -46,12 +46,9 @@
import com.google.adk.artifacts.BaseArtifactService;
import com.google.adk.events.Event;
import com.google.adk.flows.llmflows.Functions;
import com.google.adk.models.LlmRequest;
import com.google.adk.models.LlmResponse;
import com.google.adk.plugins.BasePlugin;
import com.google.adk.sessions.BaseSessionService;
import com.google.adk.sessions.GetSessionConfig;
import com.google.adk.sessions.InMemorySessionService;
import com.google.adk.sessions.Session;
import com.google.adk.sessions.SessionKey;
import com.google.adk.summarizer.EventsCompactionConfig;
Expand Down Expand Up @@ -83,7 +80,6 @@
import java.time.Instant;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.UUID;
Expand Down Expand Up @@ -592,22 +588,12 @@ public void onToolErrorCallback_error() {
@Test
public void onEventCallback_success() {
when(plugin.onEventCallback(any(), any()))
.thenAnswer(
invocation -> {
Event event = invocation.getArgument(1);
return Maybe.just(
Event.builder()
.id(event.id())
.invocationId(event.invocationId())
.author("model")
.content(createContent("from plugin"))
.build());
});
.thenReturn(Maybe.just(TestUtils.createEvent("form plugin")));

List<Event> events =
runner.runAsync("user", session.id(), createContent("from user")).toList().blockingGet();

assertThat(simplifyEvents(events)).containsExactly("model: from plugin");
assertThat(simplifyEvents(events)).containsExactly("author: content for event form plugin");

verify(plugin).onEventCallback(any(), any());
}
Expand Down Expand Up @@ -1700,109 +1686,4 @@ public void runner_executesSaveArtifactFlow() {
// agent was run
assertThat(simplifyEvents(events.values())).containsExactly("test agent: from llm");
}

@Test
public void runAsync_ensuresSequentialConsistencyForTools() {
// Arrange
TestLlm testLlm =
createTestLlm(
createFunctionCallLlmResponse("call_1", "tool1", ImmutableMap.of("arg", "value1")),
createTextLlmResponse("Final response"));

LlmAgent agent =
createTestAgentBuilder(testLlm)
.tools(
ImmutableList.of(
FunctionTool.create(RaceConditionTools.class, "tool1"),
FunctionTool.create(RaceConditionTools.class, "tool2")))
.build();

BaseSessionService delegate = new InMemorySessionService();
BaseSessionService delayedSessionService = createDelayedSessionService(delegate, 0);

Runner runner =
Runner.builder()
.app(App.builder().name("test").rootAgent(agent).build())
.sessionService(delayedSessionService)
.build();
Session session = runner.sessionService().createSession("test", "user").blockingGet();

// Act
var unused =
runner
.runAsync("user", session.id(), Content.fromParts(Part.fromText("start")))
.toList()
.blockingGet();

// Assert
ImmutableList<LlmRequest> requests = ImmutableList.copyOf(testLlm.getRequests());
assertThat(requests).hasSize(2);

// Second request should contain the result of tool1
LlmRequest secondRequest = requests.get(1);
List<Content> history = secondRequest.contents();

boolean foundToolResponse =
history.stream()
.flatMap(content -> content.parts().stream().flatMap(List::stream))
.filter(part -> part.functionResponse().isPresent())
.map(part -> part.functionResponse().get())
.anyMatch(
response ->
response.name().orElse("").equals("tool1")
&& response
.response()
.map(
r ->
java.util.Objects.equals(
r, ImmutableMap.of("result", "result_value1")))
.orElse(false));

assertThat(foundToolResponse).isTrue();
}

@SuppressWarnings({"unchecked", "deprecation"})
private static BaseSessionService createDelayedSessionService(
BaseSessionService delegate, long delayMs) {
BaseSessionService delayedSessionService = mock(BaseSessionService.class);
when(delayedSessionService.createSession(anyString(), anyString(), any(Map.class), anyString()))
.thenAnswer(
inv ->
delegate.createSession(
(String) inv.getArgument(0),
(String) inv.getArgument(1),
(Map<String, Object>) inv.getArgument(2),
(String) inv.getArgument(3)));
when(delayedSessionService.createSession(anyString(), anyString()))
.thenAnswer(
inv ->
delegate.createSession((String) inv.getArgument(0), (String) inv.getArgument(1)));
when(delayedSessionService.getSession(anyString(), anyString(), anyString(), any()))
.thenAnswer(
inv ->
delegate.getSession(
(String) inv.getArgument(0),
(String) inv.getArgument(1),
(String) inv.getArgument(2),
(Optional<GetSessionConfig>) inv.getArgument(3)));
when(delayedSessionService.appendEvent(any(), any()))
.thenAnswer(
inv ->
delegate
.appendEvent(inv.getArgument(0), inv.getArgument(1))
.delay(delayMs, MILLISECONDS));
return delayedSessionService;
}

public static class RaceConditionTools {
private RaceConditionTools() {}

public static ImmutableMap<String, Object> tool1(String arg) {
return ImmutableMap.of("result", "result_" + arg);
}

public static ImmutableMap<String, Object> tool2(String input) {
return ImmutableMap.of("status", "received_" + input);
}
}
}
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