1. jstat -gc pid
Can display gc information, check the number of gc, and time.
The last five items are the number of young gc, the time of young gc, the number of full gc, the time of full gc, and the total time of gc.
2.jstat -gccapacity pid
It can display the usage and size of the three generations (young, old, perm) objects in the VM memory,
For example: PGCMN shows the minimum perm memory usage, PGCMX shows the perm maximum memory usage,
PGC is the current newly generated perm memory usage, PC is the previous perm memory usage.
Others can be analogized according to this, OC is the pure occupancy in old.
3.jstat -gcutil pid
Statistics gc information statistics.
It can also be written as the following information:
PID | xargs jstat -gcutil
4.jstat -gcnew pid
Information about young generation objects.
5.jstat -gcnewcapacity pid
Information about young generation objects and their occupancy.
6.jstat -gcold pid
Information about the old generation object.
7.stat -gcoldcapacity pid
Information about old generation objects and their occupancy.
8.jstat -gcpermcapacity pid
Information about the perm object and its occupancy.
9.jstat -class pid
Displays information such as the number of loaded classes and the space they occupy.
10.jstat -compiler pid
Displays information such as the number of VM real-time compilations.
11.stat -printcompilation pid
Information about the current VM execution.
Chinese explanation of some terms:
SOC: The capacity (bytes) of the first survivor (survivor area) in the young generation
S1C: The capacity of the second survivor (survivor area) in the young generation (bytes)
S0U: The currently used space (bytes) of the first survivor (survivor area) in the young generation
S1U: The currently used space (bytes) of the second survivor (survivor area) in the young generation
EC: The capacity of Eden (Garden of Eden) in the young generation (bytes)
EU: Eden (Eden) in the young generation currently used space (bytes)
OC: capacity of the Old generation (bytes)
OU: Old generation currently used space (bytes)
PC: Perm (Persistent Generation) capacity (bytes)
PU: Perm (persistent generation) currently used space (bytes)
YGC: The number of gc in the young generation from application startup to sampling time
YGCT: The time (s) used by gc in the young generation from the application startup to the sampling time
FGC: The number of GCs in the old generation (full GC) from application startup to sampling time
FGCT: The time (s) from the application startup to the old generation (full gc) gc of the sampling era
GCT: The total time (s) used by gc from application startup to sampling
NGCMN: Initialized (minimum) size (bytes) in young generation (young)
NGCMX: The maximum capacity (bytes) of the young generation (young)
NGC: The current capacity (bytes) in the young generation (young)
OGCMN: initialized (minimum) size (bytes) in old generation
OGCMX: the maximum capacity of the old generation (bytes)
OGC: the current newly generated capacity of the old generation (bytes)
PGCMN: initialized (minimum) size (bytes) in perm generation
PGCMX: Maximum capacity of perm generation (bytes)
PGC: The current newly generated capacity of the perm generation (bytes)
S0: The percentage of the current capacity used by the first survivor (survivor area) in the young generation
S1: The percentage of the current capacity used by the second survivor (survivor area) in the young generation
E: The percentage of the current capacity used by Eden (Eden) in the young generation
O: The percentage of the current capacity used by the old generation
P: The percentage of the current capacity used by the perm generation
S0CMX: The maximum capacity (bytes) of the first survivor (survivor area) in the young generation
S1CMX: The maximum capacity (bytes) of the second survivor (survivor area) in the young generation
ECMX: The maximum capacity of Eden (Eden) in the young generation (bytes)
DSS: The capacity (bytes) of the survivor (survivor area) currently required (the Eden area is full)
TT: Hold count limit
MTT: Maximum number of holdings