I want to make a copy of the current running application , like Chromium browser , when i click on some button.
For now i'm using:
QProcess::startDetached( QApplication::applicationFilePath() );
But this is not cloning from the running application.
EDIT
I tried to fork() , and got a X11 error:
XX: Fatal IO error: client killed
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
RenRenPhotoFetch: ../../src/xcb_io.c:273: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.
What do you mean by "cloning"? If you mean a Unix-style fork() creating an identical copy of the process: There isn't a cross-platform API for this in Qt, as fork() is a Unix thing and not available on e.g. Windows. If you only target Unix, you can of course can just call fork().
Related
ASP.NET WebAPI2 application on .NET 4.6.2, hosted on IIS on Windows Server 2016. From time to time, there is a lot (hundreds) of requests stuck for hours (despite the fact I have request timeout 60s set) with no CPU usage. So, I took the memory dump of w3wp process, along with sos.dll, clr.dll and mscordacwks.dll and all my project's dlls and pdbs from bin directory from server and used WinDbg as described in many blogs and tutorials. But, in all of them, they are able to directly see CLR stack by calling ~*e !clrstack. I can see CLR stacktrace for some Redis and ApplicationInsights workers, but for all other managed threads I can see only:
OS Thread Id: 0x1124 (3)
Child SP IP Call Site
GetFrameContext failed: 1
0000000000000000 0000000000000000
!dumpstack for any of these gives just this:
0:181> !dumpstack
OS Thread Id: 0x1754 (181)
Current frame: ntdll!NtWaitForSingleObject+0x14
Child-SP RetAddr Caller, Callee
000000b942c7f6a0 00007fff33d63acf KERNELBASE!WaitForSingleObjectEx+0x8f, calling ntdll!NtWaitForSingleObject
000000b942c7f740 00007fff253377a6 clr!CLRSemaphore::Wait+0x8a, calling kernel32!WaitForSingleObjectEx
000000b942c7f7b0 00007fff25335331 clr!GCCoop::GCCoop+0xe, calling clr!GetThread
000000b942c7f800 00007fff25337916 clr!ThreadpoolMgr::UnfairSemaphore::Wait+0xf1, calling clr!CLRSemaphore::Wait
000000b942c7f840 00007fff253378b1 clr!ThreadpoolMgr::WorkerThreadStart+0x2d1, calling clr!ThreadpoolMgr::UnfairSemaphore::Wait
000000b942c7f8e0 00007fff253d952f clr!Thread::intermediateThreadProc+0x86
000000b942c7f9e0 00007fff253d950f clr!Thread::intermediateThreadProc+0x66, calling clr!_chkstk
000000b942c7fa20 00007fff37568364 kernel32!BaseThreadInitThunk+0x14, calling ntdll!LdrpDispatchUserCallTarget
000000b942c7fa50 00007fff3773e821 ntdll!RtlUserThreadStart+0x21, calling ntdll!LdrpDispatchUserCallTarget
So I have no idea, where to look for bug in my code.
(here is the full result:
https://gist.github.com/rouen-sk/eff11844557521de367fa9182cb94a82
and here is the results of !threads:
https://gist.github.com/rouen-sk/b61cba97a4d8300c08d6a8808c4bff6e)
What can I do? Google search for GetFrameContext failed gives nothing helpful.
As mentioned, this is not trivial, however you can find a case study of similar problem here: https://blogs.msdn.microsoft.com/rodneyviana/2015/03/27/the-case-of-the-non-responsive-mvc-web-application/
In a nutshell:
Download NetExt. It is the zip file here:
https://github.com/rodneyviana/netext/tree/master/Binaries
Open your dump and load NetExt
Run !windex to index the heap
Run !whttp -order -running to see a list of running requests
If the requests contains thread number you can go to the thread to see what is happening
If the requests contains --- instead of thread number, they are waiting a thread and this is a sign that some throttling is happening
If it is a WCF service, run !wservice to see the services
Run !wruntime to see runtime information
Run !wapppool to see Application Pool information
Run !wdae to list all errors
... And so it goes. When you do this again and again you will be able to spot issues easily
We have Websphere Message Broker v8.0.0.3 on Redhat Linux env, and we encounterd the following runtime error message:
BIP2057
Execution Group <insert_1> could not be started: broker name <insert_2>; UUID <insert_3>; label <insert_4>; Pub-Sub server <insert_5> (1=Yes, 0=No).
The situation is that one of the execution groups stopped (without any trace/log about it) and the wmb could not auto start with the BIP2057 error.
the weird part occurs when another EG restarted (unlinked reason to the first problem, because of some applicative errors) and then the first EG "took its place", started successfully, and now the second EG could not start for the same reason.
We have checked for user permissions or the logs without any success in identifying the problem.
Any help would be much appreciated.
Run the following service IBM MQSeries if it's not running already:
C:\Program Files (x86)\IBM\WebSphere MQ\bin\amqlsvc.exe
If it gives an
exception of Access Denied, your user must not be having rights to
log on.
Another possible resolution can be by restarting the
DataFlowEngine.exe process.
If none of the above scenarios fulfill the need, restart the system.
Does anyone understand what this RocksDB error refers to ?
/column_family.cc:275: rocksdb::ColumnFamilyData::~ColumnFamilyData():
Assertion `refs_ == 0' failed. Aborted (core dumped)
This is an assertion failure raised by RocksDB, and it intentionally terminates the execution of the program.
In general, assertions are used by programmers to ensure certain invariants in the program. Assertions have some runtime overhead, and therefore can be completely disabled. Often they are compiled into development or debug builds, but are omitted for production builds.
When an assertion fails, the program execution is intentionally aborted immediately by calling std::abort. This may lead to your OS writing a core dump (as it obviously did as the above message reveals), but if and where core dumps are written depends on the OS configuration.
In case of this specific assertion, the destructor of rocksdb::ColumnFamilyData raised the assertion because it requires its refs_ member to have a value of 0. refs_ is a reference counter and it makes sense to assert that no references are actually held when the object's destructor is called.
From just looking at the destructor code, it is unclear whether this is a bug in the RocksDB library itself, or an error caused by using it the wrong way, e.g. destroying column family objects when they are still in use by other objects.
For reference, here's the code part that raised the assertion (currently on line 365 in file rocksdb/db/column_family.cc):
ColumnFamilyData::~ColumnFamilyData() {
assert(refs_.load(std::memory_order_relaxed) == 0);
If the error persists, it may be useful if you provide the code that uses RocksDB here. Otherwise it may be impossible to find the error source.
The core dump may also provide useful information, because it contains the stack trace of the code that actually invoked the object's destructor.
I noticed that all column_family.cc errors (core_dumped, memory_order_relaxed and etc) occur after incorrect rocksdb installation. In my vagrant script i found true way.
instead of use
https://github.com/facebook/rocksdb/blob/master/INSTALL.md
i create script
cd /opt
git clone https://github.com/facebook/rocksdb.git
cd rocksdb
git checkout tags/v4.1
PORTABLE=1 make shared_lib
export LD_LIBRARY_PATH=/opt/rocksdb
LD_LIBRARY_PATH add better to your environment path(.bash_rc or /etc/environment)
Assertion refs_ == 0 fails on ~ColumnFamilyData() means the reference count of a column family is not zero when the column family is deleted. Most likely you have some un-deleted column family handles before closing the DB. Note that all column family handles must be deleted before closing the DB. Otherwise the assertion will fail.
// Before delete DB, you have to close All column families by calling
// DestroyColumnFamilyHandle() with all the handles.
static Status Open(const DBOptions& db_options, const std::string& name,
const std::vector<ColumnFamilyDescriptor>& column_families,
std::vector<ColumnFamilyHandle*>* handles, DB** dbptr);
To fix such assertion failure, making sure you delete all column family handles before closing the DB.
All, According the WAS.The document says the worker process is managed by WAS .
But I found when typing w3wp /? There is a debug flag.
-debug
This option launches a worker process using the default
application host config file. By default, it will use
site id 1.
What does mean start worker process in debug mode? In what case we want to start a work process with debug option ? thanks.
Added
I didn't known why I got a exception when run w3wp.exe -debug.
ERROR: There has been an error during processing of this command.
Please check the event log and see if any errors or warnings have been
logged.
When I checked the log. It looks like:
The World Wide Web Publishing Service failed to set the application
pool for the application '/xxxx' in site '1'. The data field contains
the error number.
According to http://support.microsoft.com/kb/183480 it switches the security context of the running user which is not its normal mode of operation - I suppose this would make it easier to then attach a debugger and other utilities.
I have a few work flows where I would like R to halt the Linux machine it's running on after completion of a script. I can think of two similar ways to do this:
run R as root and then call system("halt")
run R from a root shell script (could run the R script as any user) then have the shell script run halt after the R bit completes.
Are there other easy ways of doing this?
The use case here is for scripts running on AWS where I would like the instance to stop after script completion so that I don't get charged for machine time post job run. My instance I use for data analysis is an EBS backed instance so I don't want to terminate it, simply suspend. Issuing a halt command from inside the instance is the same effect as a stop/suspend from AWS console.
I'm impressed that works. (For anyone else surprised that an instance can stop itself, see notes 1 & 2.)
You can also try "sudo halt", as you wouldn't need to run as a root user, as long as the user account running R is capable of running sudo. This is pretty common on a lot of AMIs on EC2.
Be careful about what constitutes an assumption of R quitting - believe it or not, one can crash R. It may be better to have a separate script that watches the R pid and, once that PID is no longer active, terminates the instance. Doing this command inside of R means that if R crashes, it never reaches the call to halt. If you call it from within another script, that can be dangerous, too. If you know Linux well, what you're looking for is the PID from starting R, which you can pass to another script that checks ps, say every 1 second, and then terminates the instance once the PID is no longer running.
I think a better solution is to use the EC2 API tools (see: http://docs.amazonwebservices.com/AWSEC2/latest/APIReference/ for documentation) to terminate OR stop instances. There's a difference between the two of these, and it matters if your instance is EBS backed or S3 backed. You needn't run as root in order to terminate the instance - the fact that you have the private key and certificate shows Amazon that you're the BOSS, way above the hoi polloi who merely have root access on your instance.
Because these credentials can be used for mischief, be careful about running API tools from a given server, you'll need your certificate and private key on the server. That's a bad idea in the event that you have a security problem. It would be better to message to a master server and have it shut down the instance. If you have messaging set up in any way between instances, this can do all the work for you.
Note 1: Eric Hammond reports that the halt will only suspend an EBS instance, so you still have storage fees. If you happen to start a lot of such instances, this can clutter things up. Your original question seems unclear about whether you mean to terminate or stop an instance. He has other good advice on this page
Note 2: A short thread on the EC2 developers forum gives advice for Linux & Windows users.
Note 3: EBS instances are billed for partial hours, even when restarted. (See this thread from the developer forum.) Having an auto-suspend close to the hour mark can be useful, assuming the R process isn't working, in case one might re-task that instance (i.e. to save on not restarting). Other useful tools to consider: setTimeLimit and setSessionTimeLimit, and various checkpointing tools (I have a Q that mentions a couple). Using an auto-kill is useful if one has potentially badly behaved code.
Note 4: I recently learned of the shutdown command in package fun. This is multi-platform. See this blog post for commentary, and code is here. Dangerous stuff, but it could be useful if you want to adapt to Windows. I haven't tried it, though.
Update 1. Three more ideas:
You could use .Last() and runLast = TRUE for q() and quit(), which could shut down the instance.
If using littler or a script that invokes the script via Rscript, the same command line functions could be used.
My favorite package of today, tcltk2 has a neat timer mechanism, called tclTaskSchedule() that can be used to schedule the execution of an expression. You could then go crazy with the execution of stuff just before a hourly interval has elapsed.
system("echo 'rootpassword' | sudo halt")
However, the downside is having your root password in plain text in the script.
AFAIK those ways you mentioned are the only ones. In any case the script will have to run as root to be able to shut down the machine (if you find a way to do it without root that's possibly an exploit). You ask for an easier way but system("halt") is just an additional line at the end of your script.
sudo is an option -- it allows you to run certain commands without prompting for any password. Just put something like this in /etc/sudoers
<username> ALL=(ALL) PASSWD: ALL, NOPASSWD: /sbin/halt
(of course replacing with the name of user running R) and system('sudo halt') should just work.