100% cpu usage with 0.307 (and higher)

joakim_tosteberg · Post by **joakim_tosteberg** » 2004-03-11 05:23

If you experience 100% cpu usage in dcplusplus 0.307 it is just the program building up the hash database which can take a little time and is not a bug.
The hashing feature is enabled by default and can be disabled by uncheck Settings->Advanced->Enable TTH file hash feature.
The feature is right now only there to eliminate possible bugs with it and isn't used for downloads.

Edit: Forgot to add that it's not only there doing nothing, it's actually used for searches.

[EDIT: Added the words "(and higher)" to the subject. TheParanoidOne]

Qbert · Post by **Qbert** » 2004-03-11 06:52

I would recommend to anybody that they set the priority for DC++ to BelowNormal since its not calculating anything which you need in real-time for file hashes. The same would be a reason for safe and compressed transfers, because the compression calculations can eat up a lot of CPU, and you would probably want to be using your computer and devote the CPU to whatever youÃ¢â‚¬â„¢re doing. (This would just change the priority; it doesnÃ¢â‚¬â„¢t force DC++ to work slower. And you do not need administrator rights to lower a priority either.)

Gothic · Post by **Gothic** » 2004-03-11 21:08

quite interesting...And where can I get the new version??? It's not on official site... :wink:

TheParanoidOne · Post by **TheParanoidOne** » 2004-03-11 21:36

Gothic wrote:It's not on official site...

The "official" site is perpetually out of date. Vist the SourceForge project page.

Post by **GargoyleMT** » 2004-03-12 04:17

Qbert wrote:I would recommend to anybody that they set the priority for DC++ to BelowNormal since its not calculating anything which you need in real-time for file hashes.

The hashing thread is low priority...

Code: Select all

int HashManager::Hasher::run() {
   setThreadPriority(Thread::LOW);

Todi · Post by **Todi** » 2004-03-12 09:46

Bit offtopic, but since we're on the subject of hashes.

* /rebuilddb rebuilds the hash database and potentially reduces the size of the raw hash data file (also checks
its integrity)

Should really be /rebuild and nothing else. It seems pretty effective in getting the hashdb size down.

joakim_tosteberg · Post by **joakim_tosteberg** » 2004-03-12 16:20

One more thing I think I should add:
THen the hasing is complete does the cpu usage go back to normal as it don't have to hash anymore.

Guitarm · Post by **Guitarm** » 2004-03-14 22:01

Ok, I'm not sure if this is the right thread to report in but when I do a /rebuild one of the hubs that I'm in (or should I be disconnected form all hubs ?) writes *** Search spam detected from and then just about all the users in the hub. Since I'm not interested in making the Op's or anyone else angry I just wanna know what I've done

. The hubsoft is: YHub version: Beta 0.386f written by Yoshi.

Post by **GargoyleMT** » 2004-03-14 22:16

How long does /rebuild take? If it takes many seconds, it will starve the search manager thread of CPU time and cause it to fall behind in its processing. When it does, searches will queue up, and then trigger the search spam warning (that warning is generated in DC++, not by the hubsoft).

The only negative thing that will happen is that your DC++ will ignore the searches of those users for a short while - I'm not sure how OPs would even take note of this to get upset at you. (And you can achieve the same thing by doing any CPU intensive task - like playing a game.)

Guitarm · Post by **Guitarm** » 2004-03-14 22:40

Oh, ok no worries then, (thanks for clarifying)

The rebuild, by the way, takes approx. 10 minutes and I'ts actually a tiny bit of a problem because I get 99% CPU usage and the machine is somewhat unusable...

But you said somewhere in another thread (and I also looked it up in the code) that threadPriority for /rebuild was set to LOW but that doesn't help the CPU in this case does it ?. The DC++ process is at normal priority and.....Well the machine is.....slow

Post by **GargoyleMT** » 2004-03-14 23:26

The thread priority of the hashing is Low (look up). However, the priority on /rebuild is not - it's run in the main UI thread, and this is why the GUI is unresponsive.

On my system, HashData.dat was 192mb a couple days ago, so I did a /rebuild - it also took a couple of minutes, but the hash file is down to 60mb. I didn't watch memory during that time, or the explorer, but essentially it's compacting/rewriting that data file - pretty heady stuff.

Guitarm · Post by **Guitarm** » 2004-03-15 08:11

GargoyleMT wrote:pretty heady stuff.

Yes, I agree, I wouldn't say I understand all of it but looking at the code and seeing it "in action" I realize that it does alot of work and that has to cost.
By the way, I've made my first ugly hack (then I mean ugly) to the code and it actually worked so I'm a bit pleased over here

Thanks for your answers, it's always clarifying to talk to you!

xforx · Post by **xforx** » 2004-03-16 15:18

Hi, what events trigger the hash file to be rebuilt or to add hashes into it? I guess on startup if changes in share are detected and maybe when a new file is added to share... Are there others?

Post by **GargoyleMT** » 2004-03-16 20:08

xforx wrote:I guess on startup if changes in share are detected and maybe when a new file is added to share... Are there others?

On startup, the hashmanger reads known root hashes and path/filenames into memory. HashManager gets the list of files in your share from ShareManager - if there are new files in it, or if they have changed size (maybe date as well), they get (re)hashed. By default, share refreshes happen hourly - files aren't actively monitored - discovering new files to hash happens only when a share refresh is done.

Woody · Post by **Woody** » 2004-03-24 11:12

Call me stupid, but what is hashing for? Is it something to do with downloading the same file from more than one user? And what is the long hashing number I see in people's filelists?

TheParanoidOne · Post by **TheParanoidOne** » 2004-03-24 11:44

Woody wrote:Call me stupid, but what is hashing for? Is it something to do with downloading the same file from more than one user? And what is the long hashing number I see in people's filelists?

The basic idea of hashing is calculating a value from the file which will uniquely identify it based on the file contents. You can then add sources for a file regardless of what the file has been called. There are other advantages as well, which you can find by reading around the topic here.

Guest · Post by **Guest** » 2004-03-28 15:13

uncheck Settings->Advanced->Enable TTH file hash feature.

where do you find that...i can't

Xan1977 · Post by **Xan1977** » 2006-04-01 01:20

Moved from FAQ, not relevant anymore.

DC++

100% cpu usage with 0.307 (and higher)

100% cpu usage with 0.307 (and higher)

Re: 100% cpu usage with 0.307 (and higher)

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