Sql Profiler Trace Report Reader For Mac

SQL PROFILER TRACE REPORT READER CODE 500 ERROR

And the Mac, with access to Netware SQL, SQL Server, and Oracle databases.The goal of the tutorial series is to develop a decently featured microblogging application that demonstrating total lack of originality I have decided to call microblog.NOTE: This article was revised in September 2014 to be in sync with current versions of Python and Flask.Here is an index of all the articles in the series that have been published to date: This has a blocked process report which can tell you what the problem is, and give a good indication as to how to correct it.This is the sixteenth article in the series in which I document my experience writing web applications in Python using the Flask microframework.4GL (Fourth Generation Language) tools for creating screens, reports and. The roadmap viewer also provides access to accelerators like templates.Many SQL Server developers and DBAs have, in the past, had their own favourite diagnostic Stored Procedures for investigating blocking issues, but since SQL Server 2005, it is a good idea to use the SQL Profiler for all but the most complex problems. Q&A for database professionals who wish to improve their database skills and learn from others in the community Stack Exchange network consists of 178 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.(Great news! There is a new version of this tutorial!)The PDE 4092 is the web-based Student Assistance Programs (SAP) reporting form.

This should help us realize that no matter how careful we are and how much we test our application there is a good chance we will miss some bugs. Recently, a reader of this blog (Hi, George!) reported a strange database bug that we are going to debug today. Part XVIII: Deployment on the Heroku CloudOur little microblog application is starting to feel decent enough for a release, so it is time to start thinking about cleaning things up as much as we can. Part XVII: Deployment on Linux (even on the Raspberry Pi!) Part XVI: Debugging, Testing and Profiling (this article)

The BugThis problem was found by a reader of this blog, after he implemented a new function that allows users to delete their own posts. We will look at profiling techniques to find the parts of our application that are slow.Sounds good? Let's get started then. We will specifically look at measuring how much of our application our unit tests are exercising, something called test coverage.And finally, we will think about another type of problems that many applications can suffer from, bad performance.

Sql Profiler Trace Report Reader Code 500 Error

Assuming we know nothing about the problem, we now need to figure out what happened from the stack trace alone. As an extra option, we have also enabled an email based logger that will send the people in the admin list an email when an error is written to the log message.So for a bug like the one above we would get some debugging information captured in two places, the log file and an email sent to us.A stack trace isn't much to go on, but it's far better than nothing. Flask itself writes the stack trace of any exceptions that aren't handled before ending the request with a code 500 error. Back then we created a logger that writes to a log file, so that the application can write debugging or diagnostic information at run time. Debugging issues from the fieldIf you recall the unit testing article, we enabled a couple of debugging services to run on the production version of our application. Since we are now in production mode we will not see error messages or stack traces.

Without really understanding much of what's going on in this code we know there is a session '1' (which we can assume is the first session ever created) that for some reason didn't get deleted like normal sessions do when the request that created them ends. Luckily, trying to do this in the development version of the application does reproduce, and this is a bit better because when the exception occurs in development mode we get Flask's web based stack trace instead of the 500.html template.The web stack trace is nice because it allows you to inspect code and evaluate expressions all from the browser. There is a different problem here that causes two sessions to be active at the same time, while there should only be one.To see if we can learn more about the problem we should try to reproduce the bug in a more controlled environment. But we are using Python's development web server which is single threaded, so that could not be our case. But we still don't know why.If you look at the text of the exception in the bottom most line of the stack trace the problem appears to be that the Post object is attached to a session '1' from before, and now we are trying to attach the same object to another session '3'.If you Google the exception message you will find that most people having issues with this are using a multithreaded web server, and they get two requests trying to add the same object to different sessions at the same time. If we start at the bottom and we go up one frame at a time we'll find that the fourth frame is in our app/views.py, more specifically in the db.session.delete(post) statement in our delete() view function.Now we know that SQLAlchemy is unable to register the deletion of this post in the database session.

For this task we will use the debugger that comes with Python, appropriately called pdb.But what class are we looking for? Let's go back to the web based stack trace and look some more there. Breakpoints are one of the basic features found in debuggers. At this point it is possible to inspect the program, like obtaining the stack trace at the time of interruption, checking or even changing variable values, etc. A breakpoint is a command that interrupts the program when certain condition is met. Using the Python DebuggerThe easiest way to find out who is creating an object is to put a breakpoint in the object's constructor.

Sql Profiler Trace Report Reader For Mac