我试图寻找ClusterListener的示例或用法来优化和改进与MongoDB Java客户端集成的服务的调试信息。
我们如何使用Replication有效地改进我们的Mongo群集？
答案 0 :(得分：7)
<强> TL; DR
ClusterListener接口可用于监控复制集的某些方面，但是如果您想深入挖掘和/或是否想要查询ClusterListener事件之外的复制集状态提供回调，然后您可能更喜欢调用replSetGetStatus命令并检查其输出。
<强>详细
ClusterListener提供回调功能，可让您观看/回复对复制品的更改。例如，以下CLusterListener ...
public class LoggingClusterListener implements ClusterListener {
private static final Logger logger = LoggerFactory.getLogger(LoggingClusterListener.class);
@Override
public void clusterOpening(final ClusterOpeningEvent clusterOpeningEvent) {
logger.info("clusterOpening: {}", clusterOpeningEvent.getClusterId().getValue());
}
@Override
public void clusterClosed(final ClusterClosedEvent clusterClosedEvent) {
logger.info("clusterClosed: {}", clusterClosedEvent.getClusterId().getValue());
}
@Override
public void clusterDescriptionChanged(final ClusterDescriptionChangedEvent event) {
logger.info("clusterDescriptionChanged: {}", event.getClusterId().getValue());
for (ServerDescription sd : event.getNewDescription().getServerDescriptions()) {
logger.info("{} / {} / {} / {}", sd.getType(), sd.getCanonicalAddress(), sd.getState().name());
}
}
}
...与此类MongoClient相关联时......
final MongoClientOptions options = MongoClientOptions.builder()
.addClusterListener(new LoggingClusterListener())
.build();
return new MongoClient(serverAddresses, options);
...将发出以下日志记录：
// cluster starting up ...
2017-08-17 12:49:55,977 [main] clusterOpening: 599582e36d47c231ec963b0b
2017-08-17 12:49:56,076 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] clusterDescriptionChanged: 599582e36d47c231ec963b0b
2017-08-17 12:49:56,076 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostB:27017] clusterDescriptionChanged: 599582e36d47c231ec963b0b
2017-08-17 12:49:56,076 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostC:27017] clusterDescriptionChanged: 599582e36d47c231ec963b0b
2017-08-17 12:49:56,076 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] clusterDescriptionChanged 599582e36d47c231ec963b0b
2017-08-17 12:49:56,076 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] REPLICA_SET_OTHER / hostB:27017 / CONNECTED / {}
2017-08-17 12:49:56,077 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] REPLICA_SET_OTHER / hostC:27017 / CONNECTED / {}
2017-08-17 12:49:56,077 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] REPLICA_SET_SECONDARY / hostA:27017 / CONNECTED / {}
// ... the primary fails over to hostA:27017
2017-08-17 12:50:06,080 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] clusterDescriptionChanged: 599582e36d47c231ec963b0b
2017-08-17 12:50:06,080 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] REPLICA_SET_OTHER / hostB:27017 / CONNECTED / {}
2017-08-17 12:50:06,080 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] REPLICA_SET_SECONDARY / hostC:27017 / CONNECTED / {}
2017-08-17 12:50:06,080 [cluster-ClusterId{value='599582e36d47c231ec963b0b', description='null'}-hostA:27017] REPLICA_SET_PRIMARY / hostA:27017 / CONNECTED / {}
2017-08-17 12:50:07,126 [main] clusterClosed: 599582e36d47c231ec963b0b
也许这对您来说已经足够了，但如果没有，例如您想要主动监控replicaset状态 - 而不是仅在下列情况之一发生时进行响应......
...那么您可能更愿意定期采样复制集状态并对结果进行报告/记录/警报。您可以通过执行replSetGetStatus命令并询问结果来执行此操作。此命令返回一个BsonDocument（其格式描述为here），可以查询和记录。
记录状态文档是最简单的响应，但可以通过根据文档内容提出警报来增强该方法以形成监控解决方案的基础。
以下代码读取replicaset状态文档，询问它（包括计算复制延迟）并记录输出。
MongoReplicaSetStatusLogger mongoReplicaSetStatusLogger = new MongoReplicaSetStatusLogger();
// periodically ...
MongoClient mongoClient = getMongoClient();
MongoDatabase admin = mongoClient.getDatabase("admin");
BsonDocument commandResult = admin.runCommand(new BsonDocument("replSetGetStatus", new BsonInt32(1)), BsonDocument.class);
mongoReplicaSetStatusLogger.report(commandResult);
这是MongoReplicaSetStatusLogger实施：
import org.bson.BsonDocument;
import org.bson.BsonInvalidOperationException;
import org.bson.BsonNumber;
import org.bson.BsonValue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Optional;
public class MongoReplicaSetStatusLogger {
private static final Logger logger = LoggerFactory.getLogger(MongoReplicaSetStatusLogger.class);
private static final SimpleDateFormat dateFormatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss,SSSZ");
private static final String DEFAULT_VALUE = "UNKNOWN";
private static final String MEMBERS = "members";
public void report(BsonDocument replicasetStatusDocument) {
if (hasMembers(replicasetStatusDocument)) {
replicasetStatusDocument.getArray(MEMBERS).stream()
.filter(BsonValue::isDocument)
.map(memberDocument -> (BsonDocument) memberDocument)
.forEach(memberDocument -> logMemberDocument(memberDocument));
} else {
logger.warn("The replicaset status document does not contain a '{}' attributes, perhaps there has been " +
"a MongoDB upgrade and the format has changed!", MEMBERS);
}
}
private boolean hasMembers(BsonDocument replicasetStatusDocument) {
return replicasetStatusDocument.containsKey(MEMBERS) && replicasetStatusDocument.get(MEMBERS).isArray();
}
private void logMemberDocument(BsonDocument memberDocument) {
StringBuilder stringBuilder = new StringBuilder()
.append(logAttribute("node", getStringValue(memberDocument, "name")))
.append(logAttribute("health", getNumericValue(memberDocument, "health")))
.append(logAttribute("state", getStringValue(memberDocument, "stateStr")))
.append(logAttribute("uptime(s)", getNumericValue(memberDocument, "uptime")))
.append(logAttribute("lastOptime", getDateTimeValue(memberDocument, "optimeDate")))
.append(logAttribute("lastHeartbeat", getDateTimeValue(memberDocument, "lastHeartbeat")))
.append(logAttribute("lastHeartbeatRecv", getDateTimeValue(memberDocument, "lastHeartbeatRecv")))
.append(logAttribute("ping(ms)", getNumericValue(memberDocument, "pingMs")))
.append(logAttribute("replicationLag(s)", getReplicationLag(memberDocument)));
logger.error(stringBuilder.toString());
}
private String logAttribute(String key, Optional<String> value) {
return new StringBuilder(key).append("=").append(value.orElse(DEFAULT_VALUE)).append("|").toString();
}
private Optional<String> getStringValue(BsonDocument memberDocument, String key) {
if (memberDocument.containsKey(key)) {
try {
return Optional.of(memberDocument.getString(key).getValue().toUpperCase());
} catch (BsonInvalidOperationException e) {
logger.warn("Exception reading: {} from replicaset status document, message: {}.", key, e.getMessage());
}
}
return Optional.empty();
}
private Optional<String> getNumericValue(BsonDocument memberDocument, String key) {
if (memberDocument.containsKey(key)) {
BsonNumber bsonNumber = memberDocument.getNumber(key);
if (bsonNumber.isInt32()) {
return Optional.of(Integer.toString(bsonNumber.intValue()));
} else if (bsonNumber.isInt64()) {
return Optional.of(Long.toString(bsonNumber.longValue()));
} else if (bsonNumber.isDouble()) {
return Optional.of(Double.toString(bsonNumber.doubleValue()));
}
}
return Optional.empty();
}
private Optional<String> getDateTimeValue(BsonDocument memberDocument, String key) {
if (memberDocument.containsKey(key)) {
try {
return Optional.of(dateFormatter.format(new Date(memberDocument.getDateTime(key).getValue())));
} catch (BsonInvalidOperationException e) {
logger.warn("Exception reading: {} from replicaset status document due to: {}!", key, e.getMessage());
}
}
return Optional.empty();
}
private Optional<String> getReplicationLag(BsonDocument memberDocument) {
if (memberDocument.containsKey("optimeDate") && memberDocument.containsKey("lastHeartbeat")) {
try {
long optimeDate = memberDocument.getDateTime("optimeDate").getValue();
long lastHeartbeat = memberDocument.getDateTime("lastHeartbeat").getValue();
long replicationLag = lastHeartbeat - optimeDate;
return Optional.of(Long.toString(replicationLag));
} catch (BsonInvalidOperationException e) {
logger.warn("Exception reading 'optimeDate' or 'lastHeartbeat' from replicaset status document due to: {}!", e.getMessage());
} catch (IllegalArgumentException e) {
logger.warn("Exception calculating the replication lag due to: {}!", e.getMessage());
}
}
return Optional.empty();
}
}
这是输出的一个例子：
2017-08-17 15:44:35,192|[main]|ERROR|MongoReplicaSetStatusLogger|node=hostA:27017|health=1.0|state=PRIMARY|uptime(s)=21|lastOptime=2017-08-17T15:43:32,000+0100|lastHeartbeat=UNKNOWN|lastHeartbeatRecv=UNKNOWN|ping(ms)=UNKNOWN|replicationLag(s)=UNKNOWN|
2017-08-17 15:44:35,193|[main]|ERROR|MongoReplicaSetStatusLogger|node=hostB:27017|health=1.0|state=SECONDARY|uptime(s)=17|lastOptime=2017-08-17T15:43:20,000+0100|lastHeartbeat=2017-08-17T15:43:35,443+0100|lastHeartbeatRecv=2017-08-17T15:43:36,412+0100|ping(ms)=0|replicationLag(s)=15443|
2017-08-17 15:44:35,193|[main]|ERROR|MongoReplicaSetStatusLogger|node=hostC:27017|health=1.0|state=SECONDARY|uptime(s)=17|lastOptime=2017-08-17T15:43:20,000+0100|lastHeartbeat=2017-08-17T15:43:35,444+0100|lastHeartbeatRecv=2017-08-17T15:43:36,470+0100|ping(ms)=0|replicationLag(s)=15444|