Log a warning if determining the app's PID takes too long

Closes gh-31572

Author: wilkinsona

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/system/ApplicationPid.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,10 @@
 import java.nio.file.attribute.PosixFilePermission;
 import java.util.Set;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.core.log.LogMessage;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
@@ -36,9 +40,13 @@
  */
 public class ApplicationPid {
 
+	private static final Log logger = LogFactory.getLog(ApplicationPid.class);
+
 	private static final PosixFilePermission[] WRITE_PERMISSIONS = { PosixFilePermission.OWNER_WRITE,
 			PosixFilePermission.GROUP_WRITE, PosixFilePermission.OTHERS_WRITE };
 
+	private static final long JVM_NAME_RESOLVE_THRESHOLD = 200;
+
 	private final String pid;
 
 	public ApplicationPid() {
@@ -51,14 +59,36 @@ protected ApplicationPid(String pid) {
 
 	private String getPid() {
 		try {
-			String jvmName = ManagementFactory.getRuntimeMXBean().getName();
+			String jvmName = resolveJvmName();
 			return jvmName.split("@")[0];
 		}
 		catch (Throwable ex) {
 			return null;
 		}
 	}
 
+	private String resolveJvmName() {
+		long startTime = System.currentTimeMillis();
+		String jvmName = ManagementFactory.getRuntimeMXBean().getName();
+		long elapsed = System.currentTimeMillis() - startTime;
+		if (elapsed > JVM_NAME_RESOLVE_THRESHOLD) {
+			logger.warn(LogMessage.of(() -> {
+				StringBuilder warning = new StringBuilder();
+				warning.append("ManagementFactory.getRuntimeMXBean().getName() took ");
+				warning.append(elapsed);
+				warning.append(" milliseconds to respond.");
+				warning.append(" This may be due to slow host name resolution.");
+				warning.append(" Please verify your network configuration");
+				if (System.getProperty("os.name").toLowerCase().contains("mac")) {
+					warning.append(" (macOS machines may need to add entries to /etc/hosts)");
+				}
+				warning.append(".");
+				return warning;
+			}));
+		}
+		return jvmName;
+	}
+
 	@Override
 	public boolean equals(Object obj) {
 		if (obj == this) {