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Fix: make ProjectIndex thread-safe for parallel builds (backport #12832) #12928

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Merged
gnodet merged 1 commit into from
Aug 30, 2026
+22 −4
Merged

Fix: make ProjectIndex thread-safe for parallel builds (backport #12832) #12928

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20 changes: 19 additions & 1 deletion maven-core/src/main/java/org/apache/maven/lifecycle/internal/MojoExecutor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -422,9 +422,27 @@ public List<MavenProject> executeForkedExecutions(
for (Map.Entry<String, List<MojoExecution>> fork : forkedExecutions.entrySet()) {
String projectId = fork.getKey();

int index = projectIndex.getIndices().get(projectId);
Integer idx = projectIndex.getIndices().get(projectId);
if (idx == null) {
throw new LifecycleExecutionException(
"Forked execution references project '" + projectId
+ "' which is not in the reactor. This can happen with parallel builds"
+ " (-T) or when extensions modify the session projects.",
mojoExecution,
project);
}
int index = idx;

MavenProject forkedProject = projectIndex.getProjects().get(projectId);
if (forkedProject == null) {
throw new LifecycleExecutionException(
"Forked execution references project '" + projectId
+ "' which is not in the reactor (no project instance). This can happen"
+ " with parallel builds (-T) or when extensions modify the session"
+ " projects.",
mojoExecution,
project);
}

forkedProjects.add(forkedProject);

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6 changes: 3 additions & 3 deletions maven-core/src/main/java/org/apache/maven/lifecycle/internal/ProjectIndex.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,9 +18,9 @@
*/
package org.apache.maven.lifecycle.internal;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.maven.lifecycle.internal.builder.BuilderCommon;
import org.apache.maven.project.MavenProject;
Expand All @@ -43,8 +43,8 @@ public final class ProjectIndex {
private final Map<String, Integer> indices;

public ProjectIndex(List<MavenProject> projects) {
this.projects = new HashMap<>(projects.size() * 2);
this.indices = new HashMap<>(projects.size() * 2);
this.projects = new ConcurrentHashMap<>(projects.size() * 2);
this.indices = new ConcurrentHashMap<>(projects.size() * 2);

for (int i = 0; i < projects.size(); i++) {
MavenProject project = projects.get(i);
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