I had the same problem and in my case the problem was missing and/or incorrect equals implementation on some types of fields in the entity object. At commit time, Hibernate checks ALL entities loaded in the session to check if they are dirty. If any of the entities are dirty, hibernate tries to persist them - no matter of the fact that the actual object that is requested a save operation is not related to the other entities.
When I see the warning about it synchronizing the site, I don't see anything indicating why it needed to synchronize. Since going to 10.6.1 we have been consistently been seeing the "Response already committed. Cannot forward to error page." and "This exception was through after the response was committed. Access to this resource is not allowed". Which support has said isn't something to be alarmed about and there is an enhancement request to make that to not be a severe message.
I've done this in the past (6 months ago) using a symantec page that I bookmarked, but has since been changed as they appear to have fixed the problem that required this in the first place. Now I can't find any solid info on how to restore the database and logs and then perform the restore to a recovery group from Exchange 2007. Perhaps there is a better way to do what I want in Backup Exec that I haven't found.
I am not using 'BEGIN IMMEDIATE' or 'BEGIN EXCLUSIVE' at any moment and I am still facing 'database is locked' errors, specifically between a SELECT and a DELETE within the same transaction (when an 'upgrade' of the "intent to read" lock needs to be upgraded to "intent to update" is necessary). So, could you please better describe why the request fails immediately? I can't understand why it does not respect the timeout for retries in the attempt to upgrade the lock.
Holding the "read" lock you attempt to do a "DELETE". This requires an "intent to write" lock. This will fail IMMEDIATELY (no waiting) if another connection already holds an "intent to write" lock because that other connection will require an "exclusive lock" (all readers get out) in order to "commit" its changes to the database to free the "intent to write" lock. Your holding of a "read lock" will prevent that other connection from ever being able to complete its "intent to write". No amount of waiting will resolve this "deadly embrace" so you get a BUSY error immediately so that you can abort your transaction (and release the read lock) so that the other writer can complete its transaction.
The exception, of course, is that COMMIT may return SQLITE_BUSY (after the timeout expires) if it is unable to acquire the EXCLUSIVE lock required to actually write the changes to the database (non-WAL journal) (because not all read locks have been released). (Since WAL journalling does not require exclusive access to the database (as in all readers are done) in order to commit the transaction to the database, COMMIT is also guaranteed to succeed and will not return SQLITE_BUSY).
No. Holding a "read" lock will prevent the other updater (holding the "intent to write" lock) from completing their work and committing that other transaction. You must release your read lock in order to permit the other writer to commit. (however in WAL mode you holding a read does not prevent the other writer from committing but you will still not be able to acquire an "intent to write" even after the other connection commits because you are no longer holding a "current view" of the database, unless you release and re-acquire your locks).
In our experience messaging uses are often comparatively low-throughput, but may require low end-to-end latency and often depend on the strongdurability guarantees Kafka provides.In this domain Kafka is comparable to traditional messaging systems such as ActiveMQ orRabbitMQ.Website Activity TrackingThe original use case for Kafka was to be able to rebuild a user activity tracking pipeline as a set of real-time publish-subscribe feeds.This means site activity (page views, searches, or other actions users may take) is published to central topics with one topic per activity type.These feeds are available for subscription for a range of use cases including real-time processing, real-time monitoring, and loading into Hadoop oroffline data warehousing systems for offline processing and reporting.Activity tracking is often very high volume as many activity messages are generated for each user page view.MetricsKafka is often used for operational monitoring data.This involves aggregating statistics from distributed applications to produce centralized feeds of operational data.Log AggregationMany people use Kafka as a replacement for a log aggregation solution.Log aggregation typically collects physical log files off servers and puts them in a central place (a file server or HDFS perhaps) for processing.Kafka abstracts away the details of files and gives a cleaner abstraction of log or event data as a stream of messages.This allows for lower-latency processing and easier support for multiple data sources and distributed data consumption.In comparison to log-centric systems like Scribe or Flume, Kafka offers equally good performance, stronger durability guarantees due to replication,and much lower end-to-end latency.Stream ProcessingMany users of Kafka process data in processing pipelines consisting of multiple stages, where raw input data is consumed from Kafka topics and thenaggregated, enriched, or otherwise transformed into new topics for further consumption or follow-up processing.For example, a processing pipeline for recommending news articles might crawl article content from RSS feeds and publish it to an "articles" topic;further processing might normalize or deduplicate this content and publish the cleansed article content to a new topic;a final processing stage might attempt to recommend this content to users.Such processing pipelines create graphs of real-time data flows based on the individual topics.Starting in 0.10.0.0, a light-weight but powerful stream processing library called Kafka Streamsis available in Apache Kafka to perform such data processing as described above.Apart from Kafka Streams, alternative open source stream processing tools include Apache Storm andApache Samza.Event SourcingEvent sourcing is a style of application design where state changes are logged as atime-ordered sequence of records. Kafka's support for very large stored log data makes it an excellent backend for an application built in this style.Commit LogKafka can serve as a kind of external commit-log for a distributed system. The log helps replicate data between nodes and acts as a re-syncingmechanism for failed nodes to restore their data.The log compaction feature in Kafka helps support this usage.In this usage Kafka is similar to Apache BookKeeper project. 1.3 Quick Start /*Licensed to the Apache Software Foundation (ASF) under one or morecontributor license agreements. See the NOTICE file distributed withthis work for additional information regarding copyright ownership.The ASF licenses this file to You under the Apache License, Version 2.0(the "License"); you may not use this file except in compliance withthe License. You may obtain a copy of the License at -2.0Unless required by applicable law or agreed to in writing, softwaredistributed under the License is distributed on an "AS IS" BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.See the License for the specific language governing permissions andlimitations under the License.*/// Define variables for doc templatesvar context= "version": "20", "dotVersion": "2.0", "fullDotVersion": "2.0.0", "scalaVersion": "2.11";This tutorial assumes you are starting fresh and have no existing Kafka or ZooKeeper data.Since Kafka console scripts are different for Unix-based and Windows platforms, on Windows platforms use bin\windows\ instead of bin/, and change the script extension to .bat.
NOTE: any prefixed ACLs added to a cluster, even after the cluster is fully upgraded, will be ignored should the cluster be downgraded again. Notable changes in 2.0.0