Java Debug Confusion Is a Java program debuggable only when the VM is running in Debug Mode? Is there any way to change it at runtime?
Debug a java application without starting the JVM with debug arguments Normally to attach a debuger to a running jvm you would need start the jvm with arguments such as the following:  &gt; java -Xdebug -Xrunjdwp:transport=dt_socket,address=1000,server=y,suspend=n   Now if I want to debug a process that wasn't started in debug mode, what can I do?  This situation arrises when a production system (i.e. started without debug args) exhibits a 'random' (I use the term loosely) bug. So I can't restart the jvm with the appropriate arguments, because nobody knows how to reproduce the bug again. Is it impossible to attach to the JVM in this situation?  Just to clarify it is not possible to use tools like jdb to attach to already running JVMs unless they were started in debug mode  from the JVM man page     Another way to use jdb is by attaching it to a Java VM that is   already running. A VM that is to be   debugged with jdb must be started with   the following options:
Callback animation to begin only after ALL children have finished animating Get number of unread sms Research statement ideas got used by interviewing committee How do I derive the Lorentz contraction from the invariant interval? Reviewing some basic special relativity, and I stumbled upon this problem:  From the definition of the proper time: $$c^2d\tau^2=c^2dt^2-dx^2$$ I was able to derive the time dilation formula by using $x=vt$: $$c^2d\tau^2=c^2dt^2-v^2dt^2=c^2dt^2\left(1-\frac{v^2}{c^2}\right)\rightarrow d\tau = dt\sqrt{1-\frac{v^2}{c^2}}=t/\gamma$$  Now, I would very much like to be able to derive the length contraction formula in a similar fashion, and feel strongly that this should be possible. The definition of the invariant interval is: $$ds^2=dx^2-c^2dt^2$$ using $t=\frac{x}{v}$ I tried: $$ds^2=dx^2-\frac{c^2}{v^2}dx^2=dx^2\left(1-\frac{c^2}{v^2}\right)\rightarrow ds=dx\sqrt{1-\frac{c^2}{v^2}}$$  This is where I'm stuck: I don't see how this can be converted to a Lorentz factor...  Any help that will allow me to arrive at the desired result $ds=\gamma dx$ would be very much appreciated. Can anyone help me with a solution? I wrote a regular expression which works well in a certain program (grep, sed, awk, perl, python, ruby, ksh, bash, zsh, find, emacs, vi, vim, gedit, …). But when I use it in a different program (or on a different unix variant), it stops matching. Why? SQL not engaging parallelism for extremely large query Polygon label repeated for each tile RuntimeError while executing python After downloading Matplotlib to use the Statist Pugin An error has occured while executing Python code:  RuntimeError: module compiled against API version 9 but this version of numpy is 6  Python version: 2.7.5 (default, Mar  9 2014, 22:15:05)  [GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)]  QGIS version: 2.2.0-Valmiera Valmiera,   Later on the message is that statist is also not able to run.  How to solve this problem? Allowing a group Read-Write Access to a directory Why is sample standard deviation a biased estimator of $\sigma$? Bugged display in search using negation Is it possible to add attributes at runtime or to change the value of an attribute at runtime? Two electrons, or an electron and a proton, interact with each other because of the Coulomb potential, which can also be seen in the Schrödinger equation (which is the equation that describes the motion for elementary particles).  But how do an electron and a photon interact? Why can a photon kick up an electron to a higher atomic orbital, or why is a photon emitted when an electron jumps down to a lower orbital? A photon do not have any charge, so the interaction cannot be caused by the Coulomb potential. So what is it that causes the interaction, and how does that affect the Schrödinger equation? (Or well, the relativistic version of the Schrödinger equation, since we're dealing with photons.) How do I install additional drivers? I've just installed Ubuntu and I need either video, wireless, or some sort of other manufacturer (non-opensource) driver. How can I run the tool that will fetch all of these for me? I'd like graphical instructions.  Related: How does polynomial long division work? Clean install of Windows 10 OEM: license key issues? breaking of output into new lines My rear rim brakes are squeaking loudly. I don't know what the problem is, but I am sure it has nothing to do with rain because it happens all the time even if it is dry.  Anybody have an idea what could be problem and how to solve it? It makes the rear brakes kind of useless, because if I use them I will scare the people or drivers around me. How to calculate the $H_2$ and $H_\infty$ norms of TransferFunctionModels or StateSpaceModels?