英文:
How to track and monitoring, jvm class size
问题
昨天我的JVM应用程序因CPU使用率过高而出现故障，检查根本原因是因为GC暂停了应用程序。GC需要更多的时间来清理内存，这是因为我在应用程序中引入了新的LRU缓存。所以我的问题是：
是否有办法跟踪每个JVM类别的内存使用情况？例如，我有3个类，Foo，Bar，Baz。
我想知道每个类在运行时使用了多少内存。
我有一个Datadog账户，所以我计划使用工具将这些指标发送到Datadog。
英文:
Yesterday my JVM application was broken due to high CPU usage, when checking the root cause this is because GC stop the world. The GC require more time to clean up the memory, this is because I introduce new LRU cache at the app. So my question is:
Is there any way to track how big memory group by JVM class? For example, I have 3 classes, Foo, Bar, Baz.
I want to know how big memory used by each class at run time.
I have a Datadog account, so I plan to use tools to send those metrics to Datadog.
答案1
得分: 2
你可以使用简单的 jcmd 命令行工具
jcmd <PID> GC.class_histogram | less
以下是在我的简单Clojure应用程序上运行此命令的示例：
num #instances #bytes class name (module)
-------------------------------------------------------
1: 40131 2944504 [B (java.base@14.0.1)
2: 38953 1666008 [Ljava.lang.Object; (java.base@14.0.1)
3: 7610 961920 java.lang.Class (java.base@14.0.1)
4: 36134 867216 java.lang.String (java.base@14.0.1)
5: 2353 762216 [I (java.base@14.0.1)
6: 25076 601824 clojure.lang.PersistentHashMap$BitmapIndexedNode
7: 13950 446400 java.util.concurrent.ConcurrentHashMap$Node (java.base@14.0.1)
...
英文:
You can use simple jcmd command line tool
jcmd <PID> GC.class_histogram | less
As an example of running this on my simple Clojure application:
num #instances #bytes class name (module)
-------------------------------------------------------
1: 40131 2944504 [B (java.base@14.0.1)
2: 38953 1666008 [Ljava.lang.Object; (java.base@14.0.1)
3: 7610 961920 java.lang.Class (java.base@14.0.1)
4: 36134 867216 java.lang.String (java.base@14.0.1)
5: 2353 762216 [I (java.base@14.0.1)
6: 25076 601824 clojure.lang.PersistentHashMap$BitmapIndexedNode
7: 13950 446400 java.util.concurrent.ConcurrentHashMap$Node (java.base@14.0.1)
...
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