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From linjun...@apache.org
Subject [2/8] incubator-rocketmq-site git commit: Post a blog about configurations of jvm and linux kernel.
Date Wed, 26 Jul 2017 06:58:58 GMT
Post a blog about configurations of jvm and linux kernel.


Project: http://git-wip-us.apache.org/repos/asf/incubator-rocketmq-site/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-rocketmq-site/commit/1ee03731
Tree: http://git-wip-us.apache.org/repos/asf/incubator-rocketmq-site/tree/1ee03731
Diff: http://git-wip-us.apache.org/repos/asf/incubator-rocketmq-site/diff/1ee03731

Branch: refs/heads/asf-site
Commit: 1ee03731594d0de048fe3d50f8f4e7258d531851
Parents: f5ec653
Author: yukon <yukon@apache.org>
Authored: Fri Jul 14 16:05:26 2017 +0800
Committer: yukon <yukon@apache.org>
Committed: Fri Jul 14 16:05:26 2017 +0800

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 ...7-07-14-rmq-jvm-linuxkernel-configuration.md | 78 ++++++++++++++++++++
 1 file changed, 78 insertions(+)
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http://git-wip-us.apache.org/repos/asf/incubator-rocketmq-site/blob/1ee03731/_posts/2017-07-14-rmq-jvm-linuxkernel-configuration.md
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diff --git a/_posts/2017-07-14-rmq-jvm-linuxkernel-configuration.md b/_posts/2017-07-14-rmq-jvm-linuxkernel-configuration.md
new file mode 100644
index 0000000..8f8f4a0
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+++ b/_posts/2017-07-14-rmq-jvm-linuxkernel-configuration.md
@@ -0,0 +1,78 @@
+---
+title: "RocketMQ JVM/Linux Configuration"
+categories:
+  - RocketMQ
+tags:
+  - RocketMQ
+  - Operations
+  - Configuration
+---
+
+This is an introduction for configuring RocketMQ broker JVM/OS parameters. It points out
certain specified configurations that should be thinking about before deploying RocketMQ cluster.
+
+{% include toc %}
+
+# JVM Options
+
+The latest released version of JDK 1.8 is recommended, with server compiler and a 8g heap.
Set the same Xms and Xmx value to prevent the JVM from resizing the heap for better performance.
A simple JVM configurations looks like this: 
+
+```
+-server -Xms8g -Xmx8g -Xmn4g
+```
+
+If you don't care about the boot time of RocketMQ broker, pre-touch the Java heap to make
sure that every page will be allocated during JVM initialization is a better choice. Those
who don't care about the boot time can enable it:
+
+```
+-XX:+AlwaysPreTouch
+```
+
+Disable biased locking may reduce JVM pauses: 
+
+```
+-XX:-UseBiasedLocking
+```
+
+As for garbage collection, G1 collector with JDK 1.8 is recommended:
+
+```
+-XX:+UseG1GC -XX:G1HeapRegionSize=16m -XX:G1ReservePercent=25 -XX:InitiatingHeapOccupancyPercent=30
+```
+
+These GC options looks a little aggressive, but it's proved to have good performance in our
production environment.
+
+Don't set a too small value for `-XX:MaxGCPauseMillis`, otherwise JVM will use a small young
generation to achieve this goal which will cause very frequent minor GC.
+
+And use rolling GC log file is recommended:
+
+```
+-XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=30m
+```
+
+If write GC file will increase latency of broker, consider redirect GC log file to a memory
file system:
+
+```
+-Xloggc:/dev/shm/mq_gc_%p.log
+```
+
+# Linux Kernel Parameters
+
+There is a `os.sh` script that lists a lot of kernel parameters in folder `bin` which can
be used for production use with minor changes. Below parameters need attention, and more details
please refer to documentation for /proc/sys/vm/*[1].
+
+**vm.extra_free_kbytes**, tells the VM to keep extra free memory between the threshold where
background reclaim (kswapd) kicks in, and the threshold where direct reclaim (by allocating
processes) kicks in. RocketMQ uses this parameter to avoid high latency in memory allocation.
+
+**vm.min_free_kbytes**, if you set this to lower than 1024KB, your system will
+become subtly broken, and prone to deadlock under high loads. 
+
+**vm.max_map_count**, limits the maximum number of memory map areas a process
+may have. RocketMQ will use mmap to load CommitLog and ConsumeQueue, so set a bigger value
for this parameter is recommended.
+
+**vm.swappiness**, define how aggressive the kernel will swap memory pages. Higher values
will increase agressiveness, lower values decrease the amount of swap. 10 for this value to
avoid swap latency is recommended.
+
+**File descriptor limits**, RocketMQ needs open file descriptors for files(CommitLog and
ConsumeQueue) and network connections. We recommend set 655350 for file descriptors.
+
+**Disk scheduler**, the deadline I/O scheduler is recommended for RocketMQ, which attempts
to provide a guaranteed latency for requests[2].
+
+
+# Reference
+1. https://www.kernel.org/doc/Documentation/sysctl/vm.txt
+2. https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/ch06s04s02.html
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