1.6.2 内存资源 max_memory_usage:在users.xml中,表示单次Query占用内存最大值,可以设置稍大。比如128G的内存设置为100G。 max_bytes_before_external_group_by:一般按照max_memory_usage的一般设置,当group使用内存超过阈值后会刷到磁盘运行。建议50G。 max_bytes_before_external_sort:超过时进行溢写磁盘。 max_...
根据系统资源和查询需求,调整ClickHouse的并发设置,如max_threads参数。 调整内存限制参数,如max_memory_usage,以保证查询能在限定的资源下高效运行。 处理大数据量和复杂查询场景 对于大数据量查询,可以使用LIMIT子句分批查询,降低内存消耗。 对于复杂查询,可以将查询拆分为多个简单查询,使用临时表或物化视图存储中间结果,...
When starting the Kafka broker service, you need to enable the JMX parameter configuration to facilitate the collection of various JMX indicators of Kafka for service monitoring through other applications. When the user needs to adjust the flow limit threshold, an intelligent assessment is made based...
You can fine-tune memory allocation using the deduplication property (dedupe.buffer.size), which determines the total memory allocated for cleanup tasks across all log cleaner threads. Additionally, you can establish a maximum memory usage limit by defining a percentage through the buffer.load....
通过设置MaxDirectMemory来确定 JVM 可以在内存映射中使用的内存量。 默认值为 64MB。 有可能会达到此限制。 可以通过 Ambari 将-XX:MaxDirectMemorySize=amount of memory used添加到 JVM 设置来增大此值。 需要知道节点上正在使用的内存量,以及是否有足够的可用 RAM 来支持增大此值。
static void reserveMemory(long size, int cap) { if (!memoryLimitSet && VM.isBooted()) { maxMemory = VM.maxDirectMemory(); memoryLimitSet = true; } // optimist! if (tryReserveMemory(size, cap)) { return; } final JavaLangRefAccess jlra = SharedSecrets.getJavaLangRefAccess(); // re...
此外从Kafka的设计来看,更频繁的GC是为了尽可能的触发Full Gc,因为Full Gc是回收Direct Memory的条件,而Kafka大量使用了页缓存提高数据的Log的读写速度,底层用的也是Java的Direct Memory。 InitiatingHeapOccupancyPercent 这个参数实际上出入比较大,根据源码分析在JDK8b12版本之后,以及JDK11 之前这个参数和官方的文档描述...
它们允许用户控制直接内存的数量进程可以访问的内容。 所有大小均以字节为单位指定。static void reserveMemory(long size, int cap) {if (!memoryLimitSet && VM.isBooted()) {maxMemory = VM.maxDirectMemory();memoryLimitSet = true;}// optimist!
A basic push pull test , with 12 connections on the publisher process and 3 connections on the subscriber process, with a 10 minute duration. The publisher has the 100 ms timeout and 100 max_bytes parameters set on each request so both processes have work to do Heap size limit is set ...
The number of samples to retain in memory for client quotas int 11 [1,...] low read-only quota.window.size.seconds The time span of each sample for client quotas int 1 [1,...] low read-only replication.quota.window.num The number of samples to retain in memory for replication quotas...