是否可以在JVM加载(运行)后更改/修改/添加VM参数?如果是这样,我该怎么做?
Is it possible to change/modify/adding VM parameters after the JVM is already loaded (running)? If so, how can I do it?
推荐答案对于您通过 -D设置的属性命令行上的标志,你想要 System.setProperty 。例如:
For properties you'd set via the -D flag on the command line, you want System.setProperty. For example:
System.setProperty("propname", "hello world"); // ... later ... String value = System.getProperty("propname");更新:
您无法动态启用调试,但可以在启动时启用调试,但稍后会附加调试器。使用以下命令,您可以侦听端口12345并立即启动程序(通过 suspend = n )。然后,您可以在需要时附加调试器,分离调试器,稍后再重新附加等等。
You can't enable debugging dynamically, but you can enable debugging at startup but attach a debugger later. With the following, you can listen on port 12345 and start your program running right away (via suspend=n). Then you can attach a debugger if/when you need to, detach the debugger, attach again later, etc.
-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=12345当然,即使未附加调试器,这也会损害性能,因此它只适用于开发/测试代码,而不适用于生产。为此,您需要记录,例如 log4j 。
Of course, this hurts performance even when the debugger isn't attached, so it only works well in dev/test code, not production. For that, you want logging, e.g. log4j.
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