我想指出的是,我将要描述的情况很少发生,在大多数情况下一切都按预期工作。
我的java应用程序在Pub/Sub端有1个主题和1个订阅。应用程序监听订阅,进行一些处理并发送确认回复。由于Google Pub/Sub保证至少传递一次消息,我们在我们这一端基于“objectGeneration”头和“objectId”头进行消息去重。
有时候我们会看到被确认的消息被我们的应用程序再次接受,这是意外的行为。
日志示例:
GCP订阅页面包含以下图表: StackDriver确认图表: 有什么想法是怎么回事,如何进行故障排除和修复?
我的java应用程序在Pub/Sub端有1个主题和1个订阅。应用程序监听订阅,进行一些处理并发送确认回复。由于Google Pub/Sub保证至少传递一次消息,我们在我们这一端基于“objectGeneration”头和“objectId”头进行消息去重。
有时候我们会看到被确认的消息被我们的应用程序再次接受,这是意外的行为。
日志示例:
//first
2019-12-17 20:51:57.375 INFO 1 --- [sub-subscriber3] bucketNotificationFlow : Received new message from pub-sub: GenericMessage [payload={....}, headers={.....objectGeneration=1576615916875106, eventTime=2019-12-17T20:51:56.874940Z, objectId=Small_files_bunch/100_12_1.csv, ....
....
2019-12-17 20:51:57.698 INFO 1 --- [sub-subscriber3] .i.g.PubSubMessageAcknowledgementHandler : Acknowledged message - 1576615916875106
...
//duplicate 1
2019-12-17 20:51:59.663 INFO 1 --- [sub-subscriber4] bucketNotificationFlow : Received new message from pub-sub: GenericMessage [payload={...}, headers={ objectGeneration=1576615916875106, eventTime=2019-12-17T20:51:56.874940Z, objectId=Small_files_bunch/100_12_1.csv", ....
...
2019-12-17 20:51:59.704 INFO 1 --- [sub-subscriber4] c.b.m.i.DiscardedMessagesHandler : Duplicate message received GenericMessage [ headers={idempotent.keys=[objectGeneration.1576615916875106, objectId.Small_files_bunch/100_12_1.csv], ...
....
//duplicate 2
2019-12-17 22:52:02.239 INFO 1 --- [sub-subscriber1] bucketNotificationFlow : Received new message from pub-sub: GenericMessage [payload={...}, headers={objectGeneration=1576615916875106, eventTime=2019-12-17T20:51:56.874940Z, objectId=Small_files_bunch/100_12_1.csv, ...
...
2019-12-17 22:52:02.339 INFO 1 --- [sub-subscriber1] c.b.m.i.DiscardedMessagesHandler : Duplicate message received GenericMessage [ headers={idempotent.keys=[objectGeneration.1576615916875106, objectId.Small_files_bunch/100_12_1.csv], ...
// and so on each 2 hours
确认码的代码:
var generation = message.getHeaders().get("objectGeneration");
pubSubMessage = message.getHeaders().get(GcpPubSubHeaders.ORIGINAL_MESSAGE, BasicAcknowledgeablePubsubMessage.class)
pubSubMessage.ack().addCallback(
v -> {
removeFromIdempotentStore(targetMessage, false);
log.info("Acknowledged message - {}", generation); //from logs we see that this line was invoked
},
e -> {
removeFromIdempotentStore(targetMessage, false);
log.error("Failed to acknowledge message - {}", generation, e);
}
);
GCP订阅页面包含以下图表: StackDriver确认图表: 有什么想法是怎么回事,如何进行故障排除和修复?