Fix calculation of max parallel forks for test execution (#85360) (#85403)

Author: mark-vieira

build-conventions/src/main/java/org/elasticsearch/gradle/internal/conventions/info/ParallelDetector.java

@@ -62,19 +62,25 @@ public static int findDefaultParallel(Project project) {
             } else if (isMac(project.getProviders())) {
                 // Ask macOS to count physical CPUs for us
                 ByteArrayOutputStream stdout = new ByteArrayOutputStream();
+
+                // On Apple silicon, we only want to use the performance cores
+                String query = project.getProviders().systemProperty("os.arch").getOrElse("").equals("aarch64")
+                    ? "hw.perflevel0.physicalcpu"
+                    : "hw.physicalcpu";
+
                 project.exec(spec -> {
                     spec.setExecutable("sysctl");
-                    spec.args("-n", "hw.physicalcpu");
+                    spec.args("-n", query);
                     spec.setStandardOutput(stdout);
                 });
 
                 _defaultParallel = Integer.parseInt(stdout.toString().trim());
+            } else {
+                _defaultParallel = Runtime.getRuntime().availableProcessors() / 2;
             }
-
-            _defaultParallel = Runtime.getRuntime().availableProcessors() / 2;
         }
 
-        return _defaultParallel;
+        return Math.min(_defaultParallel, project.getGradle().getStartParameter().getMaxWorkerCount());
     }
 
     private static boolean isMac(ProviderFactory providers) {

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/info/GlobalBuildInfoPlugin.java

@@ -8,7 +8,6 @@
 package org.elasticsearch.gradle.internal.info;
 
 import org.apache.commons.io.IOUtils;
-import org.elasticsearch.gradle.OS;
 import org.elasticsearch.gradle.internal.BwcVersions;
 import org.elasticsearch.gradle.internal.conventions.info.GitInfo;
 import org.elasticsearch.gradle.internal.conventions.info.ParallelDetector;
@@ -30,21 +29,17 @@
 import org.gradle.util.GradleVersion;
 
 import java.io.BufferedReader;
-import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
-import java.io.FileReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
 import java.util.Arrays;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
-import java.util.Map;
 import java.util.Random;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
@@ -55,7 +50,6 @@
 public class GlobalBuildInfoPlugin implements Plugin<Project> {
     private static final Logger LOGGER = Logging.getLogger(GlobalBuildInfoPlugin.class);
     private static final String DEFAULT_VERSION_JAVA_FILE_PATH = "server/src/main/java/org/elasticsearch/Version.java";
-    private static Integer _defaultParallel = null;
 
     private final JavaInstallationRegistry javaInstallationRegistry;
     private final JvmMetadataDetector metadataDetector;
@@ -305,56 +299,6 @@ private static String getJavaHomeEnvVarName(String version) {
         return "JAVA" + version + "_HOME";
     }
 
-    private static int findDefaultParallel(Project project) {
-        // Since it costs IO to compute this, and is done at configuration time we want to cache this if possible
-        // It's safe to store this in a static variable since it's just a primitive so leaking memory isn't an issue
-        if (_defaultParallel == null) {
-            File cpuInfoFile = new File("/proc/cpuinfo");
-            if (cpuInfoFile.exists()) {
-                // Count physical cores on any Linux distro ( don't count hyper-threading )
-                Map<String, Integer> socketToCore = new HashMap<>();
-                String currentID = "";
-
-                try (BufferedReader reader = new BufferedReader(new FileReader(cpuInfoFile))) {
-                    for (String line = reader.readLine(); line != null; line = reader.readLine()) {
-                        if (line.contains(":")) {
-                            List<String> parts = Arrays.stream(line.split(":", 2)).map(String::trim).collect(Collectors.toList());
-                            String name = parts.get(0);
-                            String value = parts.get(1);
-                            // the ID of the CPU socket
-                            if (name.equals("physical id")) {
-                                currentID = value;
-                            }
-                            // Number of cores not including hyper-threading
-                            if (name.equals("cpu cores")) {
-                                assert currentID.isEmpty() == false;
-                                socketToCore.put("currentID", Integer.valueOf(value));
-                                currentID = "";
-                            }
-                        }
-                    }
-                } catch (IOException e) {
-                    throw new UncheckedIOException(e);
-                }
-                _defaultParallel = socketToCore.values().stream().mapToInt(i -> i).sum();
-            } else if (OS.current() == OS.MAC) {
-                // Ask macOS to count physical CPUs for us
-                ByteArrayOutputStream stdout = new ByteArrayOutputStream();
-                project.exec(spec -> {
-                    spec.setExecutable("sysctl");
-                    spec.args("-n", "hw.physicalcpu");
-                    spec.setStandardOutput(stdout);
-                });
-
-                _defaultParallel = Integer.parseInt(stdout.toString().trim());
-            }
-
-            _defaultParallel = Runtime.getRuntime().availableProcessors() / 2;
-        }
-
-        return _defaultParallel;
-    }
-
     public static String getResourceContents(String resourcePath) {
         try (
             BufferedReader reader = new BufferedReader(new InputStreamReader(GlobalBuildInfoPlugin.class.getResourceAsStream(resourcePath)))