Rahul Patil: Complexities of Testing Concurrency
- Posted: Oct 14, 2008 at 9:49 AM
- 61,403 Views
- 10 Comments
Download
How do I download the videos?
- To download, right click the file type you would like and pick “Save target as…” or “Save link as…”
Why should I download videos from Channel9?
- It's an easy way to save the videos you like locally.
- You can save the videos in order to watch them offline.
- If all you want is to hear the audio, you can download the MP3!
Which version should I choose?
- If you want to view the video on your PC, Xbox or Media Center, download the High Quality WMV file (this is the highest quality version we have available).
- If you'd like a lower bitrate version, to reduce the download time or cost, then choose the Medium Quality WMV file.
- If you have a Zune, WP7, iPhone, iPad, or iPod device, choose the low or medium MP4 file.
- If you just want to hear the audio of the video, choose the MP3 file.
Right click “Save as…”
- High Quality WMV (PC, Xbox, MCE)
- MP3 (Audio only)
- MP4 (iPod, Zune HD)
- Mid Quality WMV (Lo-band, Mobile)
- WMV (WMV Video)
You've been hearing a lot lately about parallelism and concurrency here on Channel 9 and the fact that before you know, you'll be writing highly concurrent code due to the
advent of multi-core and the soon-to-be many-core (greater than eight cores) processors. It's hard if not impossible to express parallelism using mainstream general purpose programming tools (most developers compose their applications in a sequential and imperative manner).
Microsoft, along with the rest of the software tools industry, is making great strides to simply the expression of concurrency using the tools that you've grown comfortable using and rely on day to day.
Of course, the current state of tools/technology (Parallel Extensions for .NET, the Concurrency Runtime, etc) make it much easier to compose parallel tasks and move you away from programming threads explicitly. This is a huge step in the right direction, but it is only a step and much more "walking" has to be done to get us to where we need to go...
Rahul Patil is a concurrency testing expert. His is the complex lifestyle of chasing down bugs that are caused by concurrently executing code (threads). In this discussion, Rahul explains to us what the common patterns are that lead to concurreny bugs (race conditions, deadlocks, etc) and offers advice on how to catch bugs before you create them...
Enjoy.
Of course, the current state of tools/technology (Parallel Extensions for .NET, the Concurrency Runtime, etc) make it much easier to compose parallel tasks and move you away from programming threads explicitly. This is a huge step in the right direction, but it is only a step and much more "walking" has to be done to get us to where we need to go...
Rahul Patil is a concurrency testing expert. His is the complex lifestyle of chasing down bugs that are caused by concurrently executing code (threads). In this discussion, Rahul explains to us what the common patterns are that lead to concurreny bugs (race conditions, deadlocks, etc) and offers advice on how to catch bugs before you create them...
Enjoy.
Comments Closed
Comments have been closed since this content was published more than 30 days ago, but if you'd like to continue the conversation,
please create a new thread in our Forums,
or
Contact Us and let us know.
Follow the Discussion
Well, sure, if you majored in CS... Point is, not all developers out there think about threads in this context. There's nothing wrong with hammering home the basics. Rahul shows the pitfalls of testing concurrency and expresses the need for developers to think about concurrent design semantics. Certainly, most developers understand what a race condition is or what causes a deadlock. But how many general purpose developers out there express concurrency correctly and know how to test their code properly (this includes up front design, the use of static analysis tools and runtime testing)?
C
Hey charles, I regenerated my channel 9 password which was sent to my email. I used it to sign in. Now i want to change it, but the my profile page (the link to which was sent to my email ) doesnt have anything remotely related to the password thing.
I'm not sure what happened to customized password creation. I'll ask the dev team.
C
spivonious is right, this was all basics - nothing new here, really.
If a developer does not know about locks/deadlocks etc. then I'm sorry to say, but he/she is just a poor developer. This is first year's knowledge on any decent university, no major degree required. This story was good maybe for Channel8, not 9.
I can't say for all the niners, but I personally feel that we should focus on specialized tools that assist in debugging concurrent programs, rather than stating the obvious about problems in parallel programming.
Thanks for the feedback... How many of you use the tools addressed in this interview (from MSR as well as in the Windows SDK)? Do you want to learn more about them? Remember that Channel 9 is not just focused on the technology but also the people who make it. Rahul is tasked with building tests for concurency. Perhaps I should have focused more on what he does, exactly. That said, I still think this is useful information and is pertinent to even the most seasoned developer: code pattern correctness, tools for testing at compile time and run time. I'll look into getting some interviews set up where we dig into the tooling.
Keep on watching,
C
The other part, is locks. How are they going to work in the brave new world? Are we OK with just using 'locks' for everything, or is that going to be too heavy a performance hit? When you add in multiple CPUs (including GPGPUs, and caching, etc. does this make locks too expensive? Are we going to be set up with needing to either take the performance hit of more comprehensive locks, or even knowing which type of lock needs to be held when? Are the Static analysis tools enough to guarantee that locks are acquired and released int eh same order, or do we need new constructs to deal with these issues in the many-core world. I suspect that lock are a much bigger part of the problem/solution that I haven't really see talked about.
Functional programming uses immutable objects and avoids the problem, but what are the rest of us supposed to do?
I liked the presentation. There really isn't much treatment out there of best practices for concurrency testing.
Functional programming will eliminate some sources of concurrency errors if there isn't shared mutable state. However, you'll still have plenty of ordering violations in message passing. Any time you need to gather the results of multiple computations you're going to have concurrency errors of some form or another.
Check out Jinx, PetraVM's offering that helps deal with these problems. It's a tool that forces concurrency errors in parallel software to occur quickly. It's pretty complementary to most of the technologies and approaches detailed in this presentation.
http://www.petravm.com/">http://www.petravm.com
http://www.petravm.com/blog">http://www.petravm.com/blog
Remove this comment
Remove this thread
close