An AppDynamics extension to be used with a stand alone Java machine agent to provide metrics from memcached instances.
curr_items - Current number of items stored total_items - Total number of items stored since the server started bytes - Current number of bytes used to store items curr_connections - Number of open connections total_connections - Total number of connections opened since the server started running connection_structures - Number of connection structures allocated by the server reserved_fds - Number of misc fds used internally cmd_get - Cumulative number of retrieval reqs cmd_set - Cumulative number of storage reqs cmd_flush - Cumulative number of flush reqs cmd_touch - Cumulative number of touch reqs get_hits - Number of keys that have been requested and found present get_misses - Number of items that have been requested and not found delete_misses - Number of deletions reqs for missing keys delete_hits - Number of deletion reqs resulting in an item being removed. incr_misses - Number of incr reqs against missing keys. incr_hits - Number of successful incr reqs. decr_misses - Number of decr reqs against missing keys. decr_hits - Number of successful decr reqs. cas_misses - Number of CAS reqs against missing keys. cas_hits - Number of successful CAS reqs. cas_badval - Number of CAS reqs for which a key was found, but the CAS value did not match. touch_hits - Numer of keys that have been touched with a new expiration time touch_misses - Numer of items that have been touched and not found auth_cmds - Number of authentication commands handled, success or failure. auth_errors - Number of failed authentications. evictions - Number of valid items removed from cache to free memory for new items reclaimed - Number of times an entry was stored using memory from an expired entry bytes_read - Total number of bytes read by this server from network bytes_written - Total number of bytes sent by this server to network limit_maxbytes - Number of bytes this server is allowed to use for storage. threads - Number of worker threads requested. (see doc/threads.txt) conn_yields - Number of times any connection yielded to another due to hitting the -R limit. hash_bytes - Bytes currently used by hash tables expired_unfetched - Items pulled from LRU that were never touched by get/incr/append/etc before expiring evicted_unfetched - Items evicted from LRU that were never touched by get/incr/append/etc. slabs_moved - Total slab pages moved crawler_reclaimed - Total items freed by LRU Crawler
1. Download and unzip MemcachedMonitor.zip from AppSphere.
2. Copy the MemcachedMonitor directory to `<MACHINE_AGENT_HOME>/monitors`.
Note : Please make sure to not use tab (\t) while editing yaml files. You may want to validate the yaml file using a yaml validator http://yamllint.com/
1. Configure the memcached instances by editing the config.yaml file in `<MACHINE_AGENT_HOME>/monitors/MemcachedMonitor/`. Below is the format
servers: - server: "localhost:11211" displayName: localhost - server: "192.168.57.102:11211" displayName: myUbuntu metricPrefix: "Custom Metrics|Memcached|"
2. Configure the path to the config.yaml file by editing the <task-arguments> in the monitor.xml file. Below is the sample
``` <task-arguments> <!-- config file--> <argument name="config-file" is-required="true" default-value="monitors/MemcachedMonitor/config.yaml" /> .... </task-arguments> ```
Cluster level metrics :
We support cluster level metrics only if each node in the cluster have a separate machine agent installed on it. There are two configurations required for this setup
1. Make sure that nodes belonging to the same cluster have the same <tier-name> in the <MACHINE_AGENT_HOME>/conf/controller-info.xml. The tier-name here should be your cluster name.
2. Make sure that in every node in the cluster, the <MACHINE_AGENT_HOME>/monitors/MemcachedMonitor/config.yaml should emit the same metric path. To achieve this make the displayName to be empty string and remove the trailing "|" in the metricPrefix.
To make it more clear,assume that Memcached "Node A" and Memcached "Node B" belong to the same cluster "ClusterAB". In order to achieve cluster level as well as node level metrics, you should do the following
1. Both Node A and Node B should have separate machine agents installed on them. Both the machine agent should have their own Memcached extension.
2. In the Node A's and Node B's machine agents' controller-info.xml make sure that you have the tier name to be your cluster name , "ClusterAB" here. Also, nodeName in controller-info.xml is Node A and Node B resp.
3. The config.yaml for Node A and Node B should be
servers: - server: "localhost:11211" displayName: "" metricPrefix: "Custom Metrics|Memcached"
Now, if Node A and Node B are reporting say a metric called ReadLatency to the controller, with the above configuration they will be reporting it using the same metric path.
Node A reports Custom Metrics | ClusterAB | ReadLatency = 50
Node B reports Custom Metrics | ClusterAB | ReadLatency = 500
The controller will automatically average out the metrics at the cluster (tier) level as well. So you should be able to see the cluster level metrics under
Application Performance Management | Custom Metrics | ClusterAB | ReadLatency = 225
Also, now if you want to see individual node metrics you can view it under
Application Performance Management | Custom Metrics | ClusterAB | Individual Nodes | Node A | ReadLatency = 50
Application Performance Management | Custom Metrics | ClusterAB | Individual Nodes | Node B | ReadLatency = 500
Please note that for now the cluster level metrics are obtained by averaging all the individual node level metrics in a cluster.
Always feel free to fork and contribute any changes directly via GitHub
Find out more in the Community
For any support questions, please contact firstname.lastname@example.org.
|3.7 or later|
Memcached version tested on:
1.0.1 - Added support for cluster level metrics.
1.0.3 - Enhanced by adding metric overrides and fixed NPE.
2.0.1 - Delta metrics
2.0.2 - Fixed an issue caused by empty "displayName" when using cluster level metrics.