when use pthread (or QThread with moveThread function) to read data (with mutex) GUI slows.
Why?
GUI Thread and pthread worker (or Qthread) are two different thread right?
Precise that the GUI don't read/write anything of data, so they are two process not correlated.
Why this issue?
(Above example of pthred worker, while GUI Dialog is created simple with qt Creator and live in main thread)
void* task_camera_notifier(void*)
{
while(AppState::is_left_camera_in_grabbing && AppState::is_right_camera_in_grabbing)
{
camera_data left_data;
SharedData::SecureAccess_get_leftCameraFrame(left_data);
}
return NULL;
}
SharedData::SecureAccess_get_leftCameraFrame(left_data); seems a very heavy operation to me (possibly it needs to read in the image from the camera which can be pretty big, then copy it in the object). And then right after the data is just read in, the left_data goes out of scope and the image is deleted. And then again, and again. Try to include a small sleep in this while loop so that it does not eat up all system resources.
Final goal: What are you trying to achieve?
Related
I'm in the very unfortunate position of needing to interface nodejs's libuv and GLib's MainLoop on all three major OSes. I need to interleave both libuv's main loop and GLib's maing loop so that both parts of the project can be happy and live together. On unixes, that's easy enough because libuv returns a file descriptor to poll on:
GSource source;
// ...
g_source_add_unix_fd (&source->source,
uv_backend_fd (loop),
(GIOCondition) (G_IO_IN | G_IO_OUT | G_IO_ERR));
On Windows however, there isn't a file descriptor to poll on. What is available is a IO Completion Port HANDLE, under uv's loop->iocp. I'm not exactly sure how to proceed from here. I was thinking that I should probably be using the following function from GLIB:
void
g_source_add_poll (GSource *source,
GPollFD *fd);
But then I'd need to create a GPollFD from that and I'm not sure how to do it or if it's the right option. Any hint that could help me progress is welcome.
Relevant link: https://github.com/romgrk/node-gtk/blob/master/src/loop.cc#L68-L75
I’m trying to write some Rust code that uses Windows.Web.UI.Interop.WebViewControl (which is a Universal Windows Platform out-of-process wrapper expressly designed so Win32 apps can use EdgeHTML), and it’s all compiling, but not working properly at runtime.
The relevant code boils down to this, using the winit, winapi and winrt crates:
use winit::os::windows::WindowExt;
use winit::{EventsLoop, WindowBuilder};
use winapi::winrt::roapi::{RoInitialize, RO_INIT_SINGLETHREADED};
use winapi::shared::winerror::S_OK;
use winrt::{RtDefaultConstructible, RtAsyncOperation};
use winrt::windows::foundation::Rect;
use winrt::windows::web::ui::interop::WebViewControlProcess;
fn main() {
assert!(unsafe { RoInitialize(RO_INIT_SINGLETHREADED) } == S_OK);
let mut events_loop = EventsLoop::new();
let window = WindowBuilder::new()
.build(&events_loop)
.unwrap();
WebViewControlProcess::new()
.create_web_view_control_async(
window.get_hwnd() as usize as i64,
Rect {
X: 0.0,
Y: 0.0,
Width: 800.0,
Height: 600.0,
},
)
.expect("Creation call failed")
.blocking_get()
.expect("Creation async task failed")
.expect("Creation produced None");
}
The WebViewControlProcess instantiation works, and the CreateWebViewControlAsync function does seem to care about the value it received as host_window_handle (pass it 0, or one off from the actual HWND value, and it complains). Yet the IAsyncOperation stays determinedly at AsyncStatus.Started (0), and so the blocking_get() call hangs indefinitely.
A full, runnable demonstration of the issue (with a bit more instrumentation).
I get the feeling that the WebViewControlProcess is at fault: its ProcessId is stuck at 0, and it doesn’t look to have spawned any subprocess. The ProcessExited event does not seem to be being fired (I attached something to it immediately after instantiation, is there opportunity for it to be fired before that?). Calling Terminate() fails as one might expect in such a situation, E_FAIL.
Have I missed some sort of initialization for using Windows.Web.UI.Interop? Or is there some other reason why it’s not working?
It turned out that the problem was threading-related: the winit crate was doing its event loop in a different thread, and I did not realise this; I had erroneously assumed winit to be a harmless abstraction, which it turned out not quite to be.
I discovered this when I tried minimising and porting a known-functioning C++ example, this time doing all the Win32 API calls manually rather than using winit, so that the translation was correct. I got it to work, and discovered this:
The IAsyncOperation is fulfilled in the event loop, deep inside a DispatchMessageW call. That is when the Completion handler is called. Thus, for the operation to complete, you must run an event loop on the same thread. (An event loop on another thread doesn’t do anything.) Otherwise, it stays in the Started state.
Fortunately, winit is already moving to a new event loop which operates in the same thread, with the Windows implementation having landed a few days ago; when I migrated my code to use the eventloop-2.0 branch of winit, and to using the Completed handler instead of blocking_get(), it all started working.
I shall clarify about the winrt crate’s blocking_get() call which would normally be the obvious solution while prototyping: you can’t use it in this case because it causes deadlock, since it blocks until the IAsyncOperation completes, but the IAsyncOperation will not complete until you process messages in the event loop (DispatchMessageW), which will never happen because you’re blocking the thread.
Try to initialize WebViewProcessControl with winrt::init_apartment(); And it may needs a single-threaded apartment(according to the this answer).
More attention on Microsoft Edge Developer Guide:
Lastly, power users might notice the apppearance of the Desktop App
Web Viewer (previously named Win32WebViewHost), an internal system app
representing the Win32 WebView, in the following places:
● In the Windows 10 Action Center. The source of these notifications
should be understood as from a WebView hosted from a Win32 app.
● In the device access settings UI
(Settings->Privacy->Camera/Location/Microphone). Disabling any of
these settings denies access from all WebViews hosted in Win32 apps.
I launch the IShellItemImageFactory::GetImage method for each item in a folder in a number of background threads. The code looks like that:
HRESULT GetImage(IShellItemImageFactory* pImgFactory,
SIZE Size, COLORREF BkColor, HBITMAP *phbm)
{
if (pImgFactory == 0 || phbm == 0)
return E_POINTER;
*phbm = 0;
HBITMAP hBmp = 0;
HRESULT hr = pImgFactory->GetImage(Size, SIIGBF_BIGGERSIZEOK, &hBmp);
if (SUCCEEDED(hr) && hBmp)
{
*phbm = CPicture::StretchBitmap(hBmp, Size, BkColor);
}
return hr;
}
Sometimes I have the all 16 threads stuck inside call to pImgFactory->GetImage for different items. They all stuck in one and the same place, which could be seen in the provided stack. I checked that different threads process different items. What can be a cause of such strange phenomenon?
EDIT:
After David Heffernan's response I realized that the IShellItemImageFactory interface itself can be not thread safe. Our threading subsystem automatically initializes each thread as STA (by the call to CoInitialize(0) function). But may be, for IShellItemImageFactory I need MTA threads. Is there a way to discover the IShellItemImageFactory's coclass CLSID, in order to find in the Registry its threading requirements?
EDIT2:
Probably, our threading mechanism somehow related to the problem. In this specific case we use an engine that we call "Job Queue". It is non-blocking FIFO queue, which elements describe a job. The description contains pointers to job's algorithm and job's data. Typically (but not necessary) the main thread puts jobs to the queue. A free thread from thread pool may get element from the queue and perform the job. This mechanism worked well for us already a couple of years. But may be, it somehow affects icon extraction. May be, I wasn't sufficiently exact in defining the icon extracting algorithm and data. I don't know how can I determine it.
The phenomenon is not really a deadlock. It happens when extracting images of subfolders in a folder, which was not still cached by the Windows. Suppose there is a folder F with 20 subfolders F1,F2,...,F20, each of which contains 20+ other subfolders and files. If folder F is not cached, extraction of 20 images of its subfolders may take 15 - 25 min (on my Win10 8-core computer). After the all images were once extracted, repeated requests for images in that folder F are performed fast.
I'm developing a launcher for a game.
Want to intercept game's call for a function that prints text.
I don't know whether the code that contains this function is dynamically linked or statically. So I dont even know the function name.
I did intercepted some windows-api calls of this game through microsoft Detours, Ninject and some others.
But this one is not in import table either.
What should I do to catch this function call? What profiler should be used? IDA? How this could be done?
EDIT:
Finally found function address. Thanks, Skino!
Tried to hook it with Detours, injected dll. Injected DllMain:
typedef int (WINAPI *PrintTextType)(char *, int, float , int);
static PrintTextType PrintText_Origin = NULL;
int WINAPI PrintText_Hooked(char * a, int b, float c, int d)
{
return PrintText_Origin(a, b, c , d);
}
HMODULE game_dll_base;
/* game_dll_base initialization goes here */
BOOL APIENTRY DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
if(fdwReason==DLL_PROCESS_ATTACH)
{
DisableThreadLibraryCalls(hinstDLL);
DetourTransactionBegin();
DetourUpdateThread(GetCurrentThread());
PrintText_Origin = (PrintTextType)((DWORD)game_dll_base + 0x6049B0);
DetourAttach((PVOID *)&PrintText_Origin , PrintText_Hooked);
DetourTransactionCommit();
}
}
It hooks as expected. Parameter a has text that should be displayed. But when calling original function return PrintText_Origin (a, b, c , d); application crashes(http://i46.tinypic.com/ohabm.png, http://i46.tinypic.com/dfeh4.png)
Original function disassembly:
http://pastebin.com/1Ydg7NED
After Detours:
http://pastebin.com/eM3L8EJh
EDIT2:
After Detours:
http://pastebin.com/GuJXtyad
PrintText_Hooked disassembly http://pastebin.com/FPRMK5qt w3_loader.dll is the injected dll
Im bad at ASM, please tell what can be wrong ?
Want to intercept game's call for a function that prints text.
You can use a debugger for the investigative phase. Either IDA, or even Visual Studio (in combination with e.g. HxD), should do. It should be relatively easy to identify the function using the steps below:
Identify a particular fragment of text whose printing you want to trace (e.g. Hello World!)
Break the game execution at any point before the game normally prints the fragment you identified above
Search for that fragment of text† (look for either Unicode or ANSI) in the game's memory. IDA will allow you to do that IIRC, as will the free HxD (Extras > Open RAM...)
Once the address of the fragment has been identified, set a break-on-access/read data breakpoint so the debugger will give you control the moment the game attempts to read said fragment (while or immediately prior to displaying it)
Resume execution, wait for the data breakpoint to trigger
Inspect the stack trace and look for a suitable candidate for hooking
Step through from the moment the fragment is read from memory until it is printed if you want to explore additional potential hook points
†provided text is not kept compressed (or, for whatever reason, encrypted) until the very last moment
Once you are done with the investigative phase and you have identified where you'd like to inject your hook, you have two options when writing your launcher:
If, based on the above exercise, you were able to identify an export/import after all, then use any API hooking techniques
EDIT Use Microsoft Detours, making sure that you first correctly identify the calling convention (cdecl, fastcall, stdcall) of the function you are trying to detour, and use that calling convention for both the prototype of the original as well as for the implementation of the dummy. See examples.
If not, you will have to
use the Debugging API to programatically load the game
compute the hook address based on your investigative phase (either as a hard-coded offset from the module base, or by looking for the instruction bytes around the hook site‡)
set a breakpoint
resume the process
wait for the breakpoint to trigger, do whatever you have to do
resume execution, wait for the next trigger etc. again, all done programatically by your launcher via the Debugging API.
‡to be able to continue to work with eventual patch releases of the game
At this stage it sounds like you don't have a notion of what library function you're trying to hook, and you've stated it's not (obviously at least) an imported external function in the import table which probably means that the function responsible for generating the text is likely located inside the .text of the application you are disassembling directly or loaded dynamically, the text generation (especially in a game) is likely a part of the application.
In my experience, this simplest way to find code that is difficult to trace such as this is by stopping the application shortly during or before/after text is displayed and using IDA's fabulous call-graph functionality to establish what is responsible for writing it out (use watches and breakpoints liberally!)
Look carefully to calls to CreateRemoteThread or any other commonly used dynamic loading mechanism if you have reason to believe this functionality might be provided by an exported function that isn't showing up in the import table.
I strongly advice against it but for the sake of completeness, you could also hook NtSetInformationThread in the system service dispatch table. here's a good dump of the table for different Windows versions here. If you want to get the index in the table yourself you can just disassemble the NtSetInformationThread export from ntdll.dll.
I am pretty sure I am suffering from memory leakage, but I havent 100% nailed down how its happening.
The application Iv'e written downloads 2 images from a url and queues each set of images, called a transaction, into a queue to be popped off by the user interface and displayed. The images are pretty big, averaging about 2.5MB. So as a way of speeding up the user interface and making it more responsive, I pre-load each transaction images into wxImage objects and store them.
When the user pops off another transaction, I feed the preloaded image into a window object that then converts the wxImage into a bitmap and DC blits to the window. The window object is then displayed on a panel.
When the transaction is finished by the user, I destroy the window object (presumably the window goes away, as does the bitmap) and the transaction data structure is overwritten with 'None'.
However, depending on how many images ive preloaded, whether the queue size is set large and its done all at once, or whether I let a small queue size sit over time, it eventually crashes. I really cant let this happen .. :)
Anyone see any obvious logical errors in what im doing? Does python garbage collect? I dont have much experience with having to deal with memory issues.
[edit] here is the code ;) This is the code related to the thread that downloads the images - it is instanced in the main thread the runs the GUI - the download thread's main function is the 'fill_queue' function:
def fill_queue(self):
while True:
if (self.len() < self.maxqueuesize):
try:
trx_data = self.download_transaction_data(self.get_url)
for trx in trx_data:
self.download_transaction_images(trx)
if self.valid_images([trx['image_name_1'], trx['image_name_2']]):
trx = self.pre_load_images(trx)
self.append(trx)
except IOError, error:
print "Received IOError while trying to download transactions or images"
print "Error Received: ", error
except Exception, ex:
print "Caught general exception while trying to download transactions or images"
print "Error Received: ", ex
else:
time.sleep(1)
def download_transaction_images(self, data):
""" Method will download all the available images for the provided transaction """
for(a, b) in data.items():
if (b) and (a == "image_name_1" or a == "image_name_2"):
modified_url = self.images_url + self.path_from_filename(b)
download_url = modified_url + b
local_filepath = self.cache_dir + b
urllib.urlretrieve(download_url, local_filepath)
urllib.urlcleanup()
def download_transaction_data(self, trx_location):
""" Method will download transaction data and return a parsed list of hash structures """
page = urllib.urlopen(trx_location)
data = page.readlines()
page.close()
trx_list = []
trx_data = {}
for line in data:
line = line.rstrip('|!\n')
if re.search('id=', line):
fields = re.split('\|', line)
for jnd in fields:
pairs = jnd.split('=')
trx_data[pairs[0]] = pairs[1]
trx_list.append(trx_data)
return trx_list
def pre_load_images(self, trx):
""" Method will create a wxImage and load it into memory to speed the image display """
path1 = self.cache_dir + trx['image_name_1']
path2 = self.cache_dir + trx['image_name_2']
image1 = wx.Image(path1)
image2 = wx.Image(path2)
trx['loaded_image_1'] = image1
trx['loaded_image_2'] = image2
return trx
def valid_images(self, images):
""" Method verifies that the image path is valid and image is readable """
retval = True
for i in images:
if re.search('jpg', i) or re.search('jpeg', i):
imagepath = self.cache_dir + i
if not os.path.exists(imagepath) or not wx.Image.CanRead(imagepath):
retval = False
else:
retval = False
return retval
Also, I'd like to add that sometimes, just before the crash I get peculiar errors in my console, they look like corrupt image errors but the images are not corrupted, the error has happened at all stages on all images.
Application transferred too few
scanlines [2009-09-08 11:12:03] Error:
JPEG: Couldn't load - file is probably
corrupted. [2009-09-08 11:12:11]
Debug: ....\src\msw\dib.cpp(134):
'CreateDIBSection' fail ed with error
0x00000000 (the operation completed
successfully.).
These errors can happen a la carte, or all together. What I think is happening is that at some point the memory becomes corrupted and anything that happens next, if I load a new transaction, or image, or do a cropping operation - it takes a dive.
So unfortunately after trying out the suggestion of moving the pre-loading function call to wxImage into the main gui thread I am still getting the error - again it will occur after too many images have been loaded into memory or if they sit in memory for too long. Then when I attempt to crop an image the i get a memory error - something is corrupting, whether in the former case I am using too much or dont have enough (which makes no sense because I've increased my paging file size to astronomical proportions) or in the latter case where the length of time is causing a leak or corruption
The only way I think I can go at this point is to use a debugger - are there any easy ways to debug a wxPython application? I would like to see the memory usage in particular.
The main reason why I think I need to preload the images is because if I call wxImage on each image ( I show two at a time) each time i load a 'transaction' the interface from one transaction to the next is very slow and clunky - If I load them in memory its very fast - but then I get my memory error.
Two thoughts:
You do not mention if the downloading is running a separate thread (actually now I see that this is running in a separate thread, I should read more closely). I'm pretty sure that wx.Image is not thread-safe, so if you are instantiating wx.Images in a non-GUI thread, that could lead to trouble like this. (This is almost certainly the issue, most wx classes/objects/functions are not thread-safe).
I've been bitten by nasty IncRef/DecRef bugs in wxPython (due to the underlying C++ bindings) before (mostly associated with wx.Grid and associated classes). While I don't know of any with wx.Image, it wouldn't surprise me to find out you may be required to manually manage memory like you have to in wx.Grid sometimes.
Edit
You need to instantiate the wx.Image in the GUI thread, not the downloading thread (which your above code looks like you are currently instantiating in the non-GUI thread). In general this is almost always going to cause lots of problems in any GUI toolkit. You can search the wxPython mailing list for lots of emails where this is the case. Personally I would do this:
Queue for download urls.
Thread to download images.
Have the downloading thread places a disk location (watch out for race conditions!) in a separate queue and post custom wx.Event(threadsafe) (threadsafe with wx.PostEvent function) to the App thread.
Have the GUI thread pop the file locations and instantiate wx.Image ----> wx.Bitmap (maybe with wx.CallAfter to process when App is idle)
Display (Blit) as needed.