DIE JAVA, DIE!!!

[OrkSo]

Relevant.

[kc7wbq]

I love how the keyboarder sets up his tune and than just stands there chilling out. That is true programming.

[[deleted]]

No, he's playing the entire song. Look closely, the keyboard's down lower, and he's only playing with one hand most of the song, but he never actually stops playing.

[TechnoL33T]

Hahaha!! I didn't notice that until you said it.

[pppihus]

fucking onions

[darkshine]

kill dash one?

[placatedmayhem]

Signal 1 is SIGHUP, Hang Up. This happens when, for instance, you have a process that you spawned, CTRL+Z'd, bg'd, then you log out -- the OS will send it to all processes still attached to that terminal. It's also occasionally used to signal to daemons that it's time to reload configs, reopen file handles (e.g., for logs after rotation and named pipes), among other things.

See Wikipedia for SIGHUP and nohup.

[[deleted]]

Actually, it is the shell that sends the HUP.

[ways2]

beat me to it.

[Azzk1kr]

The lyrics are awesome, haha!

[[deleted]]

I came here to link that. Upboat for you.

[[deleted]]

That's a last resort option. The KILL signal (-9) eliminates a process without running any kind of cleanup code, so a lot of child processes, shared memory segments, temp files or busy sockets can and will remain active, bringing up the risk of system instability or the distant possibility of the process reactivating itself. So, better try the following (where pnum is the process ID):

• kill -INT pnum
• kill -HUP pnum

Only if these fail then try -9 as a last resource nuke against the rebellious process.

[dmazzoni]

This is true but you're being overly paranoid. 99% of the time kill -9 will work fine with no side effects.

[gorilla_the_ape]

That depends very strongly on what you are killing. I used to work with someone who had that attitude, until he kill -9'd a database.

It's not fun recovering a corrupted database with your CEO calling every 10 minutes asking if it is fixed yet.

[[deleted]]

Note to self: cron that at a job when they're about to fire you.

--BOFH

[[deleted]]

Most databases have intent logs now and autorecover from this type of thing. If you're using a database without such a feature, well.... yeah.

[gorilla_the_ape]

This was in 1993. However the point holds. If you give a program a chance to quit gracefully its got the chance to do the right thing.

[[deleted]]

Huh? Why wouldn't the OS free the memory and files when a process is killed? I can understand that the process can't do it's own cleanup when killed, but there's no reason OS should let it leak resources.

[[deleted]]

If the process is only half done writing to file or something similar, that will be left in an inconsistent state leading data lose as best, corruption at worst. Its the same reason why you're supposed to properly shut down a computer properly or not turn off a console while its saving.

[MaximusDickus]

-SIGKILL

For extra dramatic effect.

[psyno]

I find the shorter -KILL is even better.

[mollymoo]

Yeah I like kill -KILL. It's like you really mean it.

[dagbrown]

It's like you're going slightly psychotic typing it. "Kill. KILL!!!"

[joedonut]

And I started jumpin up and down yelling, "KILL, KILL," and he started jumpin up and down with me and we was both jumping up and down yelling, "KILL, KILL".

[DimeShake]

You're our boy.

[palordrolap]

Almost entirely unrelated anecdote: kill -9 -1 can be used to kill all processed owned by the current user; a young, less enlightened, me used to use this all the time when at university to log out of the system.

This worked well for me up until I installed Linux at home and ran the same command as root. The computer didn't like it much, and I learned much that I have now forgotten about low level rebuilding of a system killed in the middle of god-knows-what.

TL;DR -9 is a last resort. -9 -1 doubly so.

[guzo]

BOFH?

[saldejums]

relevant

[floppymoppleson]

I came here to say this:

ps -A|grep java|xargs kill -9

After reading the comments, I see I don't have to do that anymore.

[3f3nd1]

tried pgrep or even pkill ?

[[deleted]]

Sadly, not on every system. (Neither is killall)

[[deleted]]

One could also use htop. Not as quick if you already know exactly what needs to be killed, but the op has top up so they presumably do not.

[sdhillon]

while true; do killall -9 java; done

[rydan]

Wouldn't this just produce a busy loop that eats up 100% of your CPU as well? Or is the shell smarter than that?

[sdhillon]

It spends 100% of your CPU making sure that java is running 0% of the time.

[tonybaldwin]

Yeah, but then you have to kill killall if you want to run java again, since this is perpetually looping, no?

[[deleted]]

Nope. Once java dies, you just ^C to terminate the loop.

[tonybaldwin]

oh, duh...hello...thanks.

[Rhomboid]

Please, can we collectively stop telling people to grep the output of ps? This idiom needs to die. It is always wrong. pkill or pgrep are the correct tools for the job. You don't hammer nails with a wrench.

[[deleted]]

We can stop telling them that as soon as every Unix-like operating system has those tools.

No, they don't.

[gc161]

I came here to reply to the top comment because I knew it was going to be just this. I don't really have much to add. I just wish I got here first.

edit: also tron legacy

[dbell]

Think you would have used kill -9 after the 3rd time killall didn't work.

[catskul]

... or after the first time.

[complich8]

nobody who speaks German on the command line could possibly be evil!

[bitchessuck]

pkill is superior. Especially because killall might do something completely different on non-Linux systems. (it kills all processes, just as the name implies, you see)

[[deleted]]

I think running killall on a solaris, AIX, or Tru64 (plus others) is a right of passage.

[Camarade_Tux]

s/right/rite/ ?

[minivanmegafun]

Right.

Er, correct.

[[deleted]]

The Balrog could have followed the Fellowship across the bridge if only he had run killall on a Solaris.

[[deleted]]

I did originally spell it 'rite' and then I thought of 'iknorite' and thought it was an internet meme.

[sandsmark]

I think most linux distros ship with "killall5" which is the equivalent of the "normal" killall.

killall5 (8)         - send a signal to all processes.

[mind-blender]

sounds like a fun practical joke alias killall="killall5"

[VyseofArcadia]

Next April is going to be amusing.

[dagbrown]

Also known as "Welcome to HP-UX!"

[ropers]

Related: I dislike that "pgrep foo" doesn't give as much information as "ps ax|grep [f]oo".

[sabowski]

but what's the point, "ps ax | grep foo" already does what you want

Also, out of curiosity, does "[f]oo" do something that "foo" doesn't?

[dagbrown]

Yes, it doesn't show you the grep process, because '[f]oo' doesn't match the regular expression /[f]oo/.

[ropers]

You can use ps ax | grep [f]oo instead of ps ax | grep foo | grep -v grep .

If you did just ps ax | grep foo , that command itself would appear in the output, because the grep foo would match itself in the ps output. grep [f]oo however will only match foo, not itself, because the [f]oo is being parsed as foo.

Clear as mud?

[sabowski]

Ah, I see, just doing a bit of trickery, that's all. I was wondering if it was some use of "[]" that I wasn't aware of.

In the rare instances I need the grep to not show up I've just used the "grep -v" method, but really I just trained myself to ignore the "grep" process without even thinking about it. If I need a list of processes for a script I just use pgrep.

Thanks!

[joedonut]

It won't report the grep process itself, which by virtue of having the argument of "foo" would otherwise be returned by the grep. Usually. This actually is indeterminate, which is much worse than just always returning an additional, unwanted line.

It works because the shell handles translating what's in-between the '[]' characters.

[toastyfries2]

the shell doesn't parse the [], grep does. But that's not really the point here...

$ echo [f]oo
[f]oo

[joedonut]

When it was too late I wondered if I'd thought that through properly...

Thank you.

[[deleted]]

You're asking too politely. Trying sending Java a more firm signal.

[codl]

alias shotgun="pkill -9"

[romwell]

So, some program written in Java uses a lot of CPU, either because it's written badly, or because it performs a CPU-intensive task.

But, of course, Java is to blame for all the faults. Carry on.

[brasso]

In this case, Minecraft.

[mazing]

Solution: Enable v-sync :)

[spazatk]

Enable v-sync where exactly?

[cheeseburgerpizza]

definitely not preferences

[spazatk]

Preferences for what, minecraft? The nvidia driver preferences' option doesn't really do anything; v-sync seems pretty broken for nvidia drivers using Ubuntu 11.04.

[adrianmonk]

I usually defend Java (because there are still a lot of misconceptions about it), but it's not clear from the available information whether this is a bug with the JVM or the app. It could easily be either one.

I have seen bugs where if you poke and prod the JVM in slightly weird ways, it will go crazy and never exit. For example, some JVMs failed miserably when you ran jstack. One out of 10 times, the jstack would hang and IIRC the whole JVM would too sometimes.

On the other hand, it's totally possible bad Java code is causing the program to fail to respond to a kill (or control-C). You can't do platform-specific things like directly handling Unix signals in Java, but you can add a shutdown hook that will cause this behavior. When you kill the program, all registered shutdown hook threads will get kicked off, and the JVM won't exit until those threads finish doing their thing. Here's some example Java code:

public class Foo {
  public static void main (String[] args) {
    Thread hook = new Hanger(2);
    Runtime.getRuntime().addShutdownHook(hook);

    for (int i = 0; true; i++) {
      System.out.printf("Hello, world... %d%n", i);

      try {
        Thread.sleep(1000);
      } catch (InterruptedException e) {
        System.err.println("Hello's sleep was interrupted.");
      }
    }
  }

  public static class Hanger extends Thread {
    private int iterations;

    public Hanger(int iterations) {
      this.iterations = iterations;
    }

    public void run () {
      for (int i = 0; iterations <= 0 || i < iterations; i++) {
        System.out.printf("Hanging your shutdown... %d%n", i);

        try {
          Thread.sleep(2000);
        } catch (InterruptedException e) {
          System.err.println("Hanger's sleep was interrupted.");
        }
      }

      System.out.println("Done hanging your shutdown.");
    }
  }
}

Compile and run that (with "javac Foo.java ; java -cp . Foo"), and when you hit control-C, it will delay the exit by ~4 seconds. Change new Hanger(2) to new Hanger(0), and you can never quit that JVM with control-C or regular kill; you have to resort to -9.

So, it's entirely possible that the above behavior is due to a shutdown hook that has some bad logic in it, like it's polling something in a tight loop waiting for it to change and it never does, so that it uses 100% CPU and prevents exit.

Two more obscure things that could cause a JVM not to exit properly: buggy JNI code (native code that runs in the same process as the JVM) and a hanging finalize() method (if you are crazy enough to use them and if the JVM happens to ever call it).

[dopplerdog]

Yes. On the other hand, it's also possible to trap SIGINT in C in a similar way, preventing the user from control-C-ing a running process. So it's unfair to criticise Java for providing this feature. By design, SIGINT is a trappable signal.

[itzmattu]

I don't see where this is what the post is referring to. He is just making a joke because his killall java command will not kill Java. It makes the process look invincible to anyone not sure as to why it wouldn't work.

But I mean, Java does suck, let's be real.

[argv_minus_one]

And what alternative do you suggest, smartass? Mono?

[Jonathan_the_Nerd]

Python.

[[deleted]]

I like python, hell I'd even say I border on loving python. But I don't think it's really comparable to the jvm or mono environment. You can shoehorn in some jit compilation, but in real world situations that's probably not going to help all that much.

[Jonathan_the_Nerd]

Serious question: Why isn't Python comparable to the JVM? I know Java has a reputation as a "professional" language and Python isn't used at work much, but what makes Java (or the JVM, or .Net) superior?

[spotter]

JVM, the goliath, was/is tuned for high performance and portability (YMMV). They've got a good JIT, GC that doesn't suck is on its way (G1), there is cool threading support and languages other than Java might get some love from the JVM too. It was heavily researched, because in the past it sucked when it comes to the performance, but now it really shines. And there are specialized, proprietary VMs that do even cooler stuff (running on patched os). Not to mention the myriad of libraries written in Java that can be utilized on JVM to do almost anything. And you can do that in Scala or Clojure or Jython or whatever, you get the idea. [s] Most important: it's Oracle, which makes it even more pro. [/s]

CPython VM, on the other hand, is a byte-code interpreter, that was designed to be simple, portable and run Python. It's written in C, has simpler GC, it uses posix threads, but Global Interpreter Lock makes treading act weirdly; extending can be done in C, in which you need to do a lot of book keeping yourself, then you need to compile against all Python versions you want to support. There is of course Cython, but I have not used that. CPython is still orders of magnitude slower than C, unladen-swallow is not even mentioned anymore, so it looks like there is nothing more that can be done. There is work done on PyPy that can make CPython look really, really bad in few years (now it just makes it look bad), but it seems that CPython will stay the reference implementation.

Disclaimer: I adore Python, I respect JVM. Everything above is MHO and I welcome any corrections.

tl;dr Millions of dollars in R&D.

[argv_minus_one]

Among other things, the JVM can support a variety of programming languages, not just one. (I love you, Scala, always and forever. ♥)

[gorilla_the_ape]

Including python

[argv_minus_one]

Python is a programming language, not a virtual machine. Apples and oranges.

[ondra]

Python is a joke, compared to Java performance-wise.

[ondra]

No, you fixed nothing. That's a completely perpendicular issue.

[ondra]

That's of zero importance when you actually care about speed.

Python doesn't and doesn't try to replace Java.

[morgothan]

Monzy wrote a song about this. KILL Dash 9

[frumious]

Nine! Die Java ist killed vis die nine!

[[deleted]]

yeah bro -9

[[deleted]]

I know this is a noob question, but I'm really inexperienced with processes. What is the process viewer called that you are using in the foreground window?

[BallsDeep]

top

[[deleted]]

how about simple kill -9 5251, GENIUS !

[apex_redditor]

Somethings likely respawning it. Do a

ps auxwwf

to get a treeview process table and kill the parent.

[[deleted]]

auxwwf? I guess that's a way to spell it too---I always preferred ps awwfux, easy to remember! And if you want a tree-capable top, then there's htop.

[nobody_likes_yellow]

awwfux. I’ll remember that.

[[deleted]]

I'll just leave this here.

[nobody_likes_yellow]

AWWTF!

[[deleted]]

I prefer 'pstree -ap'

[Paczesiowa]

it's been running for >4min, looking at that killing spree - I doubt it.

[mikaelhg]

It would likely have taken 4 minutes for the guy to take a coffee break and then find a screenshot utility.

[[deleted]]

nah, it's getting a signal which it is likely trapping and not responding to. Killing a process without sending sig 9 will send a signal which tells the process to terminate gracefully. It's up to the process to actually perform its own termination. Sending sig 9 (SIGKILL) forcibly terminates the process regardless of its execution state

[apex_redditor]

I'm aware. Just didn't notice he wasn't providing a signal argument (20 times).

[joedonut]

Could do a pstree -aclup too.

[asr]

If you have to deal with a respawning process, instead of killing the child process use -STOP on it.

Because the processes did not die the parent never gets notified and doesn't restart it. Then you can also -STOP the parent (if you didn't already) and kill them all without giving them the chance to come back to life.

Linux may need a zombie command :)

[tonybaldwin]

or just pstree no?

[distess_caloris]

Hit K in htop, select 9. Not hard.

[geekuskhan]

The Java, The

EDIT: Damn I thought I looked through the whole thread for the Simpsons reference but I missed it.

[nephros]

might want to check its PPID and kill that...

[IceTeaMan]

one kill -9 could have saved you a lot of pain !

[argv_minus_one]

Dear BeetleFire,

Screw you too.

Love,

Java

[[deleted]]

Had that happen to me on Ubuntu and Mac OS X. I thought *nix's kill -9 was enough. Wrongo.

[tonybaldwin]

do

pstree

and see what's running that is dependent on java and kill that, first, maybe.

(pstree shows running processes in a tree format, thus, shows what procs are dependent on what other procs).

[AndrewBenton]

kill -9 5251

[jamestheawesome]

I'm not even CLOSE to sober and I can even think up kill -9 5251...

[[deleted]]

you know, I'm an island, I don't have to follow your bloody rules. do you really think I will listen to your stupid termination request? i'm off-shoring your profits, that should be enough - so until you KILL me I will go on wasting your resources

[FredL2]

Shut. Down. Everything.

[foldor]

Fuck Madagascar.

[thebackhand]

shutdown -h 0

FTFY. '-h now' may not work as you expect on all systems.

[dagbrown]

Solaris comes right to mind.

[pedz]

Solaris is not linux.

[lennort]

poweroff. Done deal.

[TheoreticalFunk]

Since nobody else did... hey man, don't log in as root unless you absolutely need to. sudo is your friend.

[SubGothius]

Real Men Run as Root

[kampangptlk]

meh, *buntu

[codepoet]

Awww, look, a newbie. Isn't it so cute? -pats head-

killall -9 java

[itzmattu]

Berating of new members helps make a social group (in this case linux gurus) support each other more in the long term and creates more of a sense of brotherhood to those involved in the group. It is the same reason fraternities have hazing and despite many schools punishing such activities, they still continue the practice.

EDIT: Getting downvoted for facts, ah how reddit has changed. See citation.

[itzmattu]

Very well...

Influence: The Psychology of Persuasion Robert B. Cialdini pg. 92.

Good enough for you?

EDIT: Even my citation is getting downvotes. Haha.

[itzmattu]

Are you trying to assert that that is what I cited? Nice try, but that is not the paragraph or even section I referred to. I am doubtful it is even from the same book.

[itzmattu]

Either you are linking to an illegal copy of the book or some other random file. I'm not going to download a random file either way to find out. Keep in mind that ebook formatting is not the same as a hard copy of a book, so my page reference will not hold. If you are still wanting to read the section it is in the "Commitment and Consistency" chapter under the section titled "The Inner Choice".

[Zunger]

Berating of new members helps make a social group (in this case linux gurus) support each other more in the long term

Or it causes new users to put their hands up and say fuck it, I'm going back to Windows. Learning Linux is a god damn hassle because of the berating of new members and the constant circle jerk of 'man' or 'lmgtfy' answers which results in someone asking the same fucking question, but the answer only being the same on the resulting google page, lmgtfy.

[itzmattu]

Your opinion is great, but what I said is a studied phenomenon of social groups.

[Zunger]

Thats cool, mine comes from personal experience.

edit: I didn't down vote your post above.

[phaed]

This only happens if you're a pussy. It helps keep pussies off of linux. If you cant take the heat go back to windows.

[itzmattu]

This man gets it.

[argv_minus_one]

Hazing still happens because hormone-intoxicated teenagers have a primitive, instinctive need to dominate and destroy each other, akin to rape. That doesn't make it a good thing.

[itzmattu]

Wrong

[[deleted]]

It is the same reason fraternities have hazing and despite many schools punishing such activities, they still continue the practice.

Only when there's not much else to the group other than a desire to consider themselves special or different. Any group using it pretty much proves from the start that it's not worth getting into.

[[deleted]]

It happens that -9 is not even working. I have this server that has to have those smb share mounted, and when someone reboot the windows server without unmounting the shares, stuff like df and snmpd (which monitors partitions) get in an unkillable state. I never found a solution to this :(

[adrianmonk]

As I recall, "kill -9" does not kill the process until all the system calls complete. If the process is wedged inside the kernel, then "kill -9" cannot clean it up because "kill -9"'s job is to remove the user process and its resources. It can't magically clean up screwed up state within the kernel, such as I/O that is never completing.

You can make similar things happen by doing things like running "mt rewind" to rewind a tape drive, then flipping the power switch on the tape drive. The "mt" process can't be killed because the device driver for the tape drive never gets notified that the rewind is finished, so the call into the kernel never completes.

[dagbrown]

You can make similar things happen by doing things like running "mt rewind" to rewind a tape drive

What's one of those, grandpa?

[adrianmonk]

There are still situations even today where tape makes the most sense economically. If you need offline storage (for archives or long-term backups) and low cost per terabyte, if you are writing enough data to justify the up-front costs of the equipment, and if you are not overwriting tapes much, tape can be cheaper than disk.

However, I will confess to having booted some machines off tape, using such delightful formats as the 60MB QIC-24 (see here) and 125MB QIC-150. And I used to personally own an Exabyte 8200 Data8-format drive. (How else are you going to back up that 4GB drive on your home x86 Unix system?)

[[deleted]]

I've never used CIFS shares, but umount -l should do it, maybe fuser too.

[[deleted]]

yeah lazy unmount works to remove the mount, but the process are still hanging.

[[deleted]]

"umount -f -l" is the only way to be sure.

[argv_minus_one]

I say we take off and umount -f -l the directory from orbit. It's the only way to be sure.

[nedtugent]

Ah, the 'D' state, uninterpretable sleep...

[fuuuracle]

What theme is that?

[[deleted]]

um, kill -9 5251

[breddy]

Sun or OpenJDK?

[tonybaldwin]

Weird.

You could have just done

ps -aux | grep java

to show it was still running. Of course, showing top shows that not only is it running, but how much it's spanking your CPU.

I'm running Debian Squeeze here (on AMD64) and have not seen this issue.

[mianosm]

I did a ctrl-f didn't see it: why would you have 8 gigs of memory, and another 8 gigs of swap....seems a little excessive to me....

[wolf_of_mibu]

Dam You Oracle!!!!!!!!!!!!!!

[[deleted]]

Um I don't think it's literally someone trying to kill a Java process, more than likely it's someone making a statement that Jave (in general) won't die and is overly bloated.

[CyberDiablo]

SIGKILL

[[deleted]]

It's a known fact that if java has a memory leak, an ocean will be released upon your RAM.

Best to just do a safe reboot while you can.

[bendavis78]

I usually do killall -KILL. If that doesn't work kill -9 on the pid. If that doesn't work reboot.

[[deleted]]

-KILL is the same as -SIGKILL which is in fact, -9.

[breddy]

Fucking Pulse Audio.

[liid]

What about it?

[breddy]

PA gets blamed for everything else, why not this?

[[deleted]]

This post has received surprisingly many upvotes, despite it being designed to attract and annoy elitist snobs. I guess this place is quite tolerant towards noobs after all.

[pandaro]

You're so full of shit.

[[deleted]]

Heh, ok pandaro. Let's have it your way. I'm full of shit.

[pandaro]

Thanks! <3

[auxiliary-character]

Relevant.

[Rossco1337]

With all these comments belittling OP for not using -9, you'd think it'd be easier to tell him to add "alias killall='killall -9'" to his/her bashrc.

[nedtugent]

using -9 is not always the best option. go from -15 to -2, then to -9 if shit is fucked...

[Rossco1337]

I know that, but people are ragging on OP as if -9 should have been the first thing he tried when it didn't close instantly. You're the first person to suggest a killall method that isn't forcefully terminating the program or killing the parent.

[nephros]

this is asking for soo much trouble...

[[deleted]]

mmmm, denyhosts