序

本文主要研究一下Elasticsearch的BootstrapCheck

BootstrapCheck

elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/bootstrap/BootstrapCheck.java

public interface BootstrapCheck {/*** Encapsulate the result of a bootstrap check.*/final class BootstrapCheckResult {private final String message;private static final BootstrapCheckResult SUCCESS = new BootstrapCheckResult(null);public static BootstrapCheckResult success() {return SUCCESS;}public static BootstrapCheckResult failure(final String message) {Objects.requireNonNull(message);return new BootstrapCheckResult(message);}private BootstrapCheckResult(final String message) {this.message = message;}public boolean isSuccess() {return this == SUCCESS;}public boolean isFailure() {return !isSuccess();}public String getMessage() {assert isFailure();assert message != null;return message;}}/*** Test if the node fails the check.** @param context the bootstrap context* @return the result of the bootstrap check*/BootstrapCheckResult check(BootstrapContext context);default boolean alwaysEnforce() {return false;}}
复制代码

• BootstrapCheck接口定义了check方法，该方法返回BootstrapCheckResult，另外还定义了一个default方法alwaysEnforce，默认返回false

BootstrapChecks

elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/bootstrap/BootstrapChecks.java

final class BootstrapChecks {private BootstrapChecks() {}static final String ES_ENFORCE_BOOTSTRAP_CHECKS = "es.enforce.bootstrap.checks";//......// the list of checks to executestatic List<BootstrapCheck> checks() {final List<BootstrapCheck> checks = new ArrayList<>();checks.add(new HeapSizeCheck());final FileDescriptorCheck fileDescriptorCheck= Constants.MAC_OS_X ? new OsXFileDescriptorCheck() : new FileDescriptorCheck();checks.add(fileDescriptorCheck);checks.add(new MlockallCheck());if (Constants.LINUX) {checks.add(new MaxNumberOfThreadsCheck());}if (Constants.LINUX || Constants.MAC_OS_X) {checks.add(new MaxSizeVirtualMemoryCheck());}if (Constants.LINUX || Constants.MAC_OS_X) {checks.add(new MaxFileSizeCheck());}if (Constants.LINUX) {checks.add(new MaxMapCountCheck());}checks.add(new ClientJvmCheck());checks.add(new UseSerialGCCheck());checks.add(new SystemCallFilterCheck());checks.add(new OnErrorCheck());checks.add(new OnOutOfMemoryErrorCheck());checks.add(new EarlyAccessCheck());checks.add(new G1GCCheck());checks.add(new AllPermissionCheck());checks.add(new DiscoveryConfiguredCheck());return Collections.unmodifiableList(checks);}//......
}
复制代码

• BootstrapChecks的checks方法返回了一系列BootstrapCheck，其中包括HeapSizeCheck、FileDescriptorCheck、MaxNumberOfThreadsCheck、MaxSizeVirtualMemoryCheck、MaxFileSizeCheck等

FileDescriptorCheck

    static class FileDescriptorCheck implements BootstrapCheck {private final int limit;FileDescriptorCheck() {this(65535);}protected FileDescriptorCheck(final int limit) {if (limit <= 0) {throw new IllegalArgumentException("limit must be positive but was [" + limit + "]");}this.limit = limit;}public final BootstrapCheckResult check(BootstrapContext context) {final long maxFileDescriptorCount = getMaxFileDescriptorCount();if (maxFileDescriptorCount != -1 && maxFileDescriptorCount < limit) {final String message = String.format(Locale.ROOT,"max file descriptors [%d] for elasticsearch process is too low, increase to at least [%d]",getMaxFileDescriptorCount(),limit);return BootstrapCheckResult.failure(message);} else {return BootstrapCheckResult.success();}}// visible for testinglong getMaxFileDescriptorCount() {return ProcessProbe.getInstance().getMaxFileDescriptorCount();}}
复制代码

• FileDescriptorCheck要求max file descriptors不得小于65535

ClientJvmCheck

elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/bootstrap/BootstrapChecks.java

    static class ClientJvmCheck implements BootstrapCheck {@Overridepublic BootstrapCheckResult check(BootstrapContext context) {if (getVmName().toLowerCase(Locale.ROOT).contains("client")) {final String message = String.format(Locale.ROOT,"JVM is using the client VM [%s] but should be using a server VM for the best performance",getVmName());return BootstrapCheckResult.failure(message);} else {return BootstrapCheckResult.success();}}// visible for testingString getVmName() {return JvmInfo.jvmInfo().getVmName();}}
复制代码

• ClientJvmCheck要求jvm是server VM

G1GCCheck

    static class G1GCCheck implements BootstrapCheck {@Overridepublic BootstrapCheckResult check(BootstrapContext context) {if ("Oracle Corporation".equals(jvmVendor()) && isJava8() && isG1GCEnabled()) {final String jvmVersion = jvmVersion();// HotSpot versions on Java 8 match this regular expression; note that this changes with Java 9 after JEP-223final Pattern pattern = Pattern.compile("(\\d+)\\.(\\d+)-b\\d+");final Matcher matcher = pattern.matcher(jvmVersion);final boolean matches = matcher.matches();assert matches : jvmVersion;final int major = Integer.parseInt(matcher.group(1));final int update = Integer.parseInt(matcher.group(2));// HotSpot versions for Java 8 have major version 25, the bad versions are all versions prior to update 40if (major == 25 && update < 40) {final String message = String.format(Locale.ROOT,"JVM version [%s] can cause data corruption when used with G1GC; upgrade to at least Java 8u40", jvmVersion);return BootstrapCheckResult.failure(message);}}return BootstrapCheckResult.success();}// visible for testingString jvmVendor() {return Constants.JVM_VENDOR;}// visible for testingboolean isG1GCEnabled() {assert "Oracle Corporation".equals(jvmVendor());return JvmInfo.jvmInfo().useG1GC().equals("true");}// visible for testingString jvmVersion() {assert "Oracle Corporation".equals(jvmVendor());return Constants.JVM_VERSION;}// visible for testingboolean isJava8() {assert "Oracle Corporation".equals(jvmVendor());return JavaVersion.current().equals(JavaVersion.parse("1.8"));}}
复制代码

• G1GCCheck对oracle java8开启G1的话要求update是40以后，避免data corruption

小结

• BootstrapCheck接口定义了check方法，该方法返回BootstrapCheckResult，另外还定义了一个default方法alwaysEnforce，默认返回false
• BootstrapChecks的checks方法返回了一系列BootstrapCheck，其中包括HeapSizeCheck、FileDescriptorCheck、MaxNumberOfThreadsCheck、MaxSizeVirtualMemoryCheck、MaxFileSizeCheck等
• FileDescriptorCheck要求max file descriptors不得小于65535；ClientJvmCheck要求jvm是server VM；G1GCCheck对oracle java8开启G1的话要求update是40以后，避免data corruption

doc

• BootstrapCheck