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Editor to share with you how to use the jdk tool jstat, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Jstat: virtual Machine Statistics Monitoring tool (JVM Statistics Monitoring Tool)

Description: monitor the various running states of the virtual machine: class loading, memory, garbage collection and other running data. Format: jstat [option] PID [interval] [count] Parameter: option:-class view class loading information-gc view the status of the java heap-gccapacity view the minimum and maximum capacity of each area in the heap-gcutil view each area in the heap Used space as a percentage of its total space-gccause is the same as-gcutil Also output: causes of the last GC and current GC-gcnew to view the status of the Cenozoic generation in the heap-gcnewcapacity to view the minimum and maximum capacity of the Cenozoic generation in the heap-gcold to view the status of the old age in the heap-gcoldcapacity View the minimum and maximum capacity of the old age in the heap-gcpermcapacity view the minimum and maximum capacity of the permanent generation in the heap-gcmetacapacity view the current size of the metadata space, Maximum and minimum capacity (jdk1.8) interval: indicates the interval between queries Unit: millisecond count: indicates the number of queries. If both interval and count are omitted, the default is one query. Query result identification: general: Minor GC (Young GC): YGC: the number of Minor GC since the process was started YGCT: the time spent by the Minor GC since the process was started, the number of times Full GC:FGC expressed FGCT represents time FGC: number of Full GC since the process was started FGCT: time spent by Full GC since the process was started GCT: total time spent by Minor GC and Full GC jstat-gc jstat-gcutil jstat-gccause New Generation (Young) Eden Zone in: e E: percentage of Space used in Eden Zone capacity of EC:Eden Zone (Eden Capacity) Space used in EU:Eden Zone (Eden Use) Survivor Zone in the Cenozoic era (Young): S0S1 Old Age (Old) : O permanent generation (Permanent): P jdk8: metadata space (Metaspace): compressed class space in M metadata space (Compressed Class Space): CCS Description: 1 > there is no permanent generation in jdk8. It is replaced by meta-space, which occupies local memory and does not occupy the memory of the virtual machine. 2 > Metaspace consists of two parts: Klass Metaspace and NoKlass Metaspace. 3 > M indicates the percentage used by Metaspace, and CCS represents the percentage used by Klass Metaspace (CCS=CCSU/CCSC). The value of 4 > M is more than 90%, which does not necessarily mean that metaspace has been used a lot, because the memory is slowly commit, so our denominator is gradually increasing, but when we reach a certain amount of commit, it will not grow any more. 5 > it is more reliable to judge the state of metaspace according to MC,MU,CCSC,CCSU. Note: S0/S0C/S0U, S1/S1C/S1U, O/OC/OU, P/PC/PU, M/MC/MU, CCS/CCSC/CCSU is similar to E/EC/EU LGCC: the cause of the last GC GCC: the current cause of GC jstat-gccapacity NGCMN: the minimum (initialization) capacity of the Cenozoic NGCMX: the maximum capacity of the Cenozoic NGC: the current capacity of the Cenozoic ECMX: the maximum capacity of the Eden region in the Cenozoic S0CMX, S1CMX: maximum capacity of Survivor area in Cenozoic era OGCMN: minimum (initialization) capacity of the old age OGCMX: maximum capacity of the old age OGC: current capacity of the old age PGCMN: minimum (initialization) capacity of the permanent generation PGCMX: maximum capacity of permanent generation PGC: current capacity of permanent generation jdk8: MCMN: minimum capacity of metadata space MCMX: maximum capacity of metadata space MC: size of current metadata space CCSMN: the minimum capacity of compressed class space CCS (that is, Klass Metaspace) CCSMX: the maximum capacity of compressed class space CCS (that is, Klass Metaspace) CCSC: the size of the current compressed class space CCS (that is, Klass Metaspace) jstat-gcnew TT: aging threshold. Before being moved to the old age, the number of empty survival in the Cenozoic era MTT: maximum aging threshold. DSS: the amount of space needed in the survivor area Note: units above KB are all the contents of this article entitled "how to use the jdk tool jstat". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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