bgworker | Background Worker Processes for PostgreSQL written in Go | SQL Database library
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kandi X-RAY | bgworker Summary
Background Worker Processes for PostgreSQL written in Go.
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QUESTION
I want to run llvm-slicer
(source) for PostgreSQL main executable file (i.e., PG_ROOT/src/backend/postgres
) to carry backward slicing on PostgreSQL.
llvm-slicer
runs on top of bitcode (.bc
file). I have compiled PostgreSQL via ./configure CC=clang-6.0 && make CC=clang-6.0
, duiring which, the final compile command that link many .o
files together is (very long):
ANSWER
Answered 2022-Mar-22 at 08:54Solution: whole-program-llvm.
It provides tools for building whole-program (or whole-library) LLVM bitcode files from an unmodified C or C++ source package. It currently runs on *nix platforms such as Linux, FreeBSD, and Mac OS X.
QUESTION
I'm doing my first NSIS script but i found a bump in the road. In fact i think is hard to explain only in the title, (maybe someone can help with that to) so let me explain fully:
I'm creating a installer that uses a few custom pages because i want the user select some options first (it uses nsDialogs), and depending of that do some tweaks in the with installation path (mostly autodetect it because it could depend to other things). All of this is working fine.
In some cases of that options, between checking if some files exists, it hash a file to look if the file is the one it expects (because it's going to patch it with a delta later). I used Crypto plugin or MD5 plugin, both are fine and both do what i want, but they hang the installer for a while (a second or so), i suppose because the file is a little big (it's about more than 100MB) and near that is the issue.
Normally in these cases, you select the option, goes to the next (custom) page, and in the creator function of the custom page autodetects the folder, and it directly do the file checks and when is checking the file hash, it hangs for a second and continues, but all this time hanged it only shows a blank page, because it didn't reach yet in the creator function the nsDialogs::Show instruction to show the window content. In that page you can change the folder, and if it's the case, once is changed it runs the checks again (it's a dedicated function that was called in both cases) and hangs again for a bit, but then the window shows everything and i can set a text to say something (in fact, it is what i did first), but with that automatic first time i can't do this.
That's the point: how to show something to the user to aware them about the installer is doing the hash calculations, instead showing only a blank window.
What I have tried or thought to do:
- With nsDialogs, because it did the calculations first and didn't reach the nsDialogs::Show until later, i can't display anything in the window at that point (or, at least, is what i read in all the documentation i found about that). And, like the documentation says and it was tested, everything you put after the nsDialogs::Show instruction is executed when you push the next or back button.
- Seeing that with nsDialogs at first not seems the way to go, i was searching if it's possible to show a window above the installation window (something like a MessageBox) and close it automatically, before and after the hash calculation respectively, showing only a text with a "Please wait" or kind of. But i didn't find a way to do it.
- Maybe with a timer and do the checks a few miliseconds after could be done, but it seems to me a very cheap way to do it with some issues waiting to happen, mostly because depends of the machine speed, something i could do only in a last resort if it makes to show first the window with nsDialogs::Show, and later execute the check files with a timer. But, i want to do the checks as the folder is set because that function enables the "Next" button and i want that as soon as is possible, and adding timers to this doesn't look right.
- Or is other more stylish way to do this but i didn't figure it out yet.
if it is not well understood the topic, i could add a little example tomorrow created from scratch to show this, because my main test is so big that is not point to paste all of that here.
Thanks!
EDIT:
This is the original example with the issue (Don't forget to add a path to a big file as marked):
...ANSWER
Answered 2021-Dec-15 at 02:51You are not really supposed to do heavy work on the custom pages. You can use the BgWorker plug-in to do background work. Combine that with a timer hack and you get this:
QUESTION
I've recently started to learn about async-await, and I built a simple app to practice with, now I want to run a for loop, and then in each loop, I want to append the current i
of the loop to my textbox.Text
, and I want it to run asynchronously
I couldn't directly run an async method, because it would complain that the control is being changed by a different thread than the main thread, so I found out that I have to use the BackgroundWorker
class, but in the DoWork
event handler of this BgWorker, I must use thread.sleep()
to make it run asynchronously so my UI remains responsive while the for loop is running, and if I remove the thread.sleep()
, the UI will freeze for a few seconds, and then it writes out the whole thing at once, what if I don't want that thread.sleep()
? why is it required? how is it working? can I make it run asynchronously but without thread.sleep()
?
ANSWER
Answered 2021-Oct-06 at 13:18Without the call to Thread.Sleep(100)
, the UI thread can't respond to your input because it's constantly busy updating the UI.
The Worker thread will start and call backgroundWorker1.ReportProgress(i)
immediately. Which will invoke the UI thread to update the textbox and repaint the dialog. When this is done, it will basically immediately call backgroundWorker1.ReportProgress(i)
again and to the exact same thing.
This means that the UI thread, instead of checking for events from user input, is constantly updating the textbox and repainting the dialog.
QUESTION
I have another question about threadsaftey according to memory access.
What about the synchronisation of objects passed to BackgroundWorker RunWorkerAsync(object) and returning to Result?
Lets say we have class (simplified)
We assume that threads will not access the same objects at the same time.
...ANSWER
Answered 2021-Apr-29 at 10:27A lock is only needed, when something is used by multiple things in parallel AND its content can be changed.
In your example the WorkArgs
are immutable (can only be changed by creating a new instance). In that case everything is fine. The background worker receives the args object and nobody is able to change its properties (they are read-only). Thus a lock is not needed.
Same is true for your result, cause while the value is settable within the DoWork()
method, the Completed()
callback gets a read-only property.
Depending on how often you call the DoWork()
callback and maybe the object Any
is something more specific that contains something that will be changed from the DoWork()
AND changed from outside while both methods are running, a lock could be needed.
QUESTION
Within my application, I have a button that pulls a longitude and latitude from a database and stores them into two variables stored within a class named bgworker, the variables are then displayed on screen as shown here: https://i.imgur.com/5ld231v.png
I then send the variables to my Google Maps fragment with the code:
...ANSWER
Answered 2021-Apr-01 at 14:32I have Idea make your Googlemap local and in onclick pass googleMap in Function so Change your UpdateMap to
QUESTION
I am writing a piece of C# .NET software which spawns a bunch of Background Workers. All of the workers immediately go into the "IsBusy" state, however, only 8 are ever processing through their DoWork method at once.
Is there a way to increase how many run at any one time?
This is how the code spawns the Background workers:
...ANSWER
Answered 2021-Feb-08 at 09:49Try the following
QUESTION
I am trying to create something like a background worker that monitors a database (RabbitMQ). If there is a new entry, it will notify the user in the UI.
I call my "background worker" from the appbar:
...ANSWER
Answered 2020-Oct-05 at 03:24In order to use hooks, you should convert your class into functional component. I assume you don't know about hooks and functional components.
This blog will help you understand the nuances of the conversion -> https://nimblewebdeveloper.com/blog/convert-react-class-to-function-component
Secondly, you need to know how hooks works. Refer to this -> https://reactjs.org/docs/hooks-intro.html
QUESTION
I am new to web development in Python and would really appreciate some help. I am trying to set up psycopg2/peewee on WSL (Windows machine). In my Python code I store all of the info I'll need to access a Postgres database, and then attempt to connect to the database as follows:
...ANSWER
Answered 2020-Aug-13 at 13:46The short version of the answer is that there where two instances of Postgres running in two different OS'es. The longer answer is as follows. In WSL(2) the Postgres instance pg_hba.conf
had local
set to peer
for user postgres
and md5
for all. There where md5
auth connections for localhost IPV4 and IPV6. This is why Allison could connect as database userpostgres
user from system user postgres account. Changing the local
settings to trust
allowed for connecting from any system account when not using -h
. The password connection issue with localhost
remained though. The strange part was there was no record of those connections in the Postgres logs. There was no other instance of Postgres running in WSL. After too long a thought process on my part it became apparent that there had to be a server running in Windows proper. That was the case and it was the one grabbing the localhost
connections and throwing the password errors. Shutting it down was a step to solving this. As it turns the Windows Postgres was running on port 5432
and the WSL instance 5433
and the WSL instance was only listening on localhost
. Changing the port to 5432 and listen_addresses
to '*' allowed for localhost
connection without specifying a port and local
connections.
QUESTION
I have been trying to Scrape some data from a certain web site but it seems like my code is not behaving as expected. It is just not getting me the html page.
...ANSWER
Answered 2020-Aug-09 at 11:19If you're using ScrapySharp make sure it is updated (newest) version.
To display HTML of scrapped webpage you're missing .InnerHtml
after webPage.Html
:
QUESTION
PostgreSQL makes use of background workers to allow processes working in a concurrent fashion and they have an API for backend/extension developers to control them. So far, I have managed to successfully work with this feature in a demo extension, successfully spawning a number of workers.
I am in a situation where one of my workers has to wait for another to finish. What I am doing so far is an infinite loop on an idle worker until the worker being waited for is finished, which can be quite inefficient. So I was wondering how would I go about making the idle process sleep until some signal is sent? What would I be looking for? Is there an extension which does something similar so that I could use for guidance?
...ANSWER
Answered 2020-Mar-04 at 07:11You could use advisory locks. They are not tied to transactions.
Another option is to use "light-weight locks" (LWlock), a.k.a. latches, which are available in the backend.
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