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
代码语言：javascript复制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;
}
}- 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
代码语言：javascript复制final class BootstrapChecks {
private BootstrapChecks() {
}
static final String ES_ENFORCE_BOOTSTRAP_CHECKS = "es.enforce.bootstrap.checks";
//......
// the list of checks to execute
static 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);
}
//......
}- BootstrapChecks的checks方法返回了一系列BootstrapCheck，其中包括HeapSizeCheck、FileDescriptorCheck、MaxNumberOfThreadsCheck、MaxSizeVirtualMemoryCheck、MaxFileSizeCheck等
FileDescriptorCheck
代码语言：javascript复制 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 testing
long getMaxFileDescriptorCount() {
return ProcessProbe.getInstance().getMaxFileDescriptorCount();
}
}- 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
代码语言：javascript复制 static class ClientJvmCheck implements BootstrapCheck {
@Override
public 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 testing
String getVmName() {
return JvmInfo.jvmInfo().getVmName();
}
}- ClientJvmCheck要求jvm是server VM
G1GCCheck
代码语言：javascript复制 static class G1GCCheck implements BootstrapCheck {
@Override
public 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-223
final 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 40
if (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 testing
String jvmVendor() {
return Constants.JVM_VENDOR;
}
// visible for testing
boolean isG1GCEnabled() {
assert "Oracle Corporation".equals(jvmVendor());
return JvmInfo.jvmInfo().useG1GC().equals("true");
}
// visible for testing
String jvmVersion() {
assert "Oracle Corporation".equals(jvmVendor());
return Constants.JVM_VERSION;
}
// visible for testing
boolean isJava8() {
assert "Oracle Corporation".equals(jvmVendor());
return JavaVersion.current().equals(JavaVersion.parse("1.8"));
}
}- 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
