When multiple Memcache servers are used in a cluster, removing the same cache key from every server manually can be time-consuming.<\/p>\n\n\n\n
The following Python script can be used to delete a single Memcache key or multiple Memcache keys across multiple Memcache hosts. The hosts can be grouped into different Memcache clusters, allowing you to target a specific cluster when running the script.<\/p>\n\n\n\n
Before using the script, make sure the following requirements are satisfied:<\/p>\n\n\n\n
MEMCACHE_CLUSTER<\/code> section.<\/li>\n\n\n\n- The machine running the script must have the Python Memcache module installed.<\/li>\n\n\n\n
- The origin host must be able to connect to the Memcache port, which is
11211<\/code> by default, on all Memcache servers.<\/li>\n<\/ol>\n\n\n\nImplementation<\/h2>\n\n\n\nStep 1: Configure the Memcache Clusters<\/h3>\n\n\n\n
The following script contains the Memcache cluster configuration and functions required to delete cache keys:<\/p>\n\n\n\n
#!\/usr\/bin\/python\n########Script to Delete Memcache Key########\n#Author:Dhanasekaran N\n#Email:support@pheonixsolutions.com\n\n#Version:1.0\n#############################################\nimport memcache\nfrom fabric import *\nfrom fabric.api import *\n\n#Mention your Cluster hosts and unique name\n_MEMCACHE_CLUSTER_ = {\n\u201cCluster1\u201d :[\u2018IPAddress1:<port>\u2019,\u2019IPaddress2:<port>\u2019],\n\u201cCluster2\u201d :[\u2018IPaddress3:<port>\u2019,\u2019IPaddress:<port>\u2019],\n}\ndef _run_command(host_name,verify_key):\nmc = memcache.Client([host_name], debug=0)\n#run(\u2018pwd\u2019);\nprint \u201ckey name:\u201d + verify_key;\nchecked_key=mc.get(verify_key);\nprint checked_key;\nif(checked_key is None):\nprint \u201cThe key %s doesn\u2019t exist \u201d %(verify_key)\nelse:\nprint \u201cDeleting %s from %s\u201d %(verify_key,host_name)\nmc.delete(verify_key)\n\ndef delete_memcache(delete_key=\u2019none\u2019,hosts_group=\u2019none\u2019,delete_multiple_keys=\u2019none\u2019):\nall_groups=_MEMCACHE_CLUSTER_.keys();\n#print delete_multiple_keys;\nif (delete_key==\u2019none\u2019 and delete_multiple_keys==\u2019none\u2019):\nprint \u201cNo delete Key or delete_multiple_key Mentioned\u201d;\nprint \u201cEg:fab delete_memcache:delete_key=\u2019some_key1\u2032,hosts_group=\u2019java_api'\u201d\nelif(hosts_group ==\u2019none\u2019):\nprint \u201cMention the host Group while running fab\u201d\nprint _MEMCACHE_CLUSTER_.keys();\nelse:\nif(delete_multiple_keys!=\u2019none\u2019):\nif(delete_multiple_keys):\ndelete_multiple_keys = delete_multiple_keys.split(\u201c;\u201d)\nfor cache_cluster in all_groups:\nif(cache_cluster == hosts_group):\n#print _MEMCACHE_CLUSTER_[cache_cluster];\nfor cache_cluster_hosts in _MEMCACHE_CLUSTER_[cache_cluster]:\nprint cache_cluster_hosts;\nfor delete_key in delete_multiple_keys:\nexecute(_run_command,hosts=cache_cluster_hosts,host_name=cache_cluster_hosts,verify_key=delete_key);\nelse:\nfor cache_cluster in all_groups:\nif(cache_cluster == hosts_group):\nfor cache_cluster_hosts in _MEMCACHE_CLUSTER_[cache_cluster]:\nprint cache_cluster_hosts;\nexecute(_run_command,hosts=cache_cluster_hosts,host_name=cache_cluster_hosts,verify_key=delete_key);<\/pre>\n\n\n\nStep 2: Delete a Single Memcache Key<\/h3>\n\n\n\n
To delete a single key from all hosts belonging to Cluster1<\/code>, use:<\/p>\n\n\n\nfab delete_memcache:delete_key=keyname,hosts_group=Cluster1<\/pre>\n\n\n\nThis command deletes the specified key from each Memcache host configured under Cluster1<\/code>.<\/p>\n\n\n\nStep 3: Delete Multiple Memcache Keys<\/h3>\n\n\n\n
To delete multiple keys from a specific cluster, separate the key names using ;<\/code>:<\/p>\n\n\n\nfab delete_memcache:delete_multiple_keys=keyname1;keyname2,hosts_group=Cluster1<\/pre>\n\n\n\nThis executes the deletion for each specified key across the hosts configured in Cluster1<\/code>.<\/p>\n\n\n\nStep 4: Verify the Key Before Deletion<\/h3>\n\n\n\n
The script first checks whether the specified key exists:<\/p>\n\n\n\n
checked_key=mc.get(verify_key);<\/pre>\n\n\n\nIf the key does not exist, the script displays a message indicating that the key is unavailable. If the key exists, it proceeds with the deletion:<\/p>\n\n\n\n
mc.delete(verify_key)<\/pre>\n\n\n\nThis provides a basic verification before removing the cache entry.<\/p>\n\n\n\n
Conclusion<\/h2>\n\n\n\n
Managing cache keys across multiple Memcache servers can be difficult when performed manually. This Python and Fabric-based script simplifies the process by allowing administrators to delete a single key or multiple keys across a selected Memcache cluster.<\/p>\n\n\n\n
By grouping Memcache hosts into clusters, the required cache entries can be removed from the appropriate servers using a single command.<\/p>\n\n\n\n
FAQs<\/h2>\n\n\n\n1. What is the purpose of this Memcache script?<\/h4>\n\n\n\n
The script is used to delete one or more Memcache keys across multiple hosts belonging to a configured cluster.<\/p>\n\n\n\n
2. Can I delete multiple Memcache keys at once?<\/h4>\n\n\n\n
Yes. Multiple keys can be supplied using the delete_multiple_keys<\/code> option, with each key separated by a semicolon.<\/p>\n\n\n\n3. What port does Memcache use by default?<\/h4>\n\n\n\n
Memcache commonly uses port 11211<\/code>. The script requires the origin server to have network connectivity to the configured Memcache hosts and ports.<\/p>\n\n\n\n4. Can I target a specific Memcache cluster?<\/h4>\n\n\n\n
Yes. The hosts_group<\/code> parameter allows you to specify the cluster, such as Cluster1<\/code> or Cluster2<\/code>, where the keys should be deleted.<\/p>\n\n\n\nRelated Articles<\/h2>\n\n\n\n\n- PHP Fatal Error: Class ‘Memcache’ Not Found<\/strong> \u2013 Learn how to troubleshoot the PHP Memcache extension when the
Memcache<\/code> class is unavailable in a PHP application.
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