during block-chain download: high CPU load + GUI lags + addresses don't stay selected and lose focus (0.6.1 RC1) #1154

Verified for 0.6.1 RC1 on Windows 7 x64:

• start Bitcoin-Qt with only addr.dat, walled.dat and bitcoin.cfg files in the datadir
• click on an (receiving) address in your list while block-chain is downloading / syncing
• address is selected and marked active
• focus get's lost and address is inactive

This seems to happen everytime a new block is received, seem there is some GUI re-draw triggered that makes this focus loss happen.

Additionally I have GUI lags while downloading the block-chain + a way to high CPU load!

can you elaborate please?

Updated initial posting!

Not that is interesting, as long as the current checkpoint is active which has 168000 blocks there is no lag and no problem with selecting addresses from the list, but as soon as the current block count is recieved by a node the client starts to lag / missbehave.

The focus loss for addresses is indeed related to MainFrameRepaint(), if I simply empty this function no focus loss occurs. The problem with the GUI lag is that I can't reproduce it with my own builds and it only happens with the official 0.6.1 RC1 :-/.

@laanwj I need your help here, have you got any ideas? I guess it is related to your commit https://github.com/bitcoin/bitcoin/commit/98e61758744ed34e8b7f59b37edb6d09b33d5517

The address loss-of-selection should only happen when AddressBookRepaint is called, which only happens when there is an actual change to the address book. I'm not sure why it would happen on MainFrameRepaint but that's wrong behaviour, I split them on purpose.

The lag could be related. MainFrameRepaint is cheap, as "change" signals are only emitted by the models when something is found to have changed, However, AddressBookRepaint is an expensive operation, as it resynchronizes the address book, so if it somehow gets triggered every time... the expected performance would be abysmal.

Found the problem. WalletModel::update calls addressTableModel->update() ... oh my...

Thanks for spotting this.

This fixed the worst performance issue.

However, MainFrameRepaint is still called a lot. Also, every time it scans the wallet and computes the balance.

• We need some kind of rate limiting on MainFrameRepaints. There is no need to update the UI faster than say, 10 times per second, even if hundreds of blocks come in. The timer, combined with a flag maybe wasn't that bad an idea after all.
• And it would be useful to make notifications more specific. Different notifications from the core whether the balance could have changed, or the number of blocks, or the number of connections... instead of a generic call. I made a start with AddressBookRepaint.

Thanks for your quick reaction, as I'm not advanced in Qt-GUI stuff I could not have fixed it by myself. But in terms of debugging and helping we are indeed a good team :).

Will merge your fix into my local build and test it out.

An update-rate limiter would be a great idea. Value could be once every sec while block-chain is downloading and on demand, if we are up-to date, as it should not happen very often then?

I can confirm addresses now stay again selected, but as I said I can't check if CPU usage or lag is fixed, as I didn't observe this with my own builds. @laanwj Shall I let this open until the next RC or will you work-out on further commits that address the problem, so this can be closed?

Let's leave this open for now. I'll leave the other mentioned improvements for 0.7.0 as they're not as urgent as this one, and have the risk of introducing further issues into the release candidate. But it helps to leave this issue open to remind.

Reference to #1205

#1205 has improved the CPU usage during initial block download, but it feels still a bit hight. @laanwj How is CPU usage on Ubuntu with -debug -logtimestamps?

Remember that the crypto during block chain download also takes quite some computational power. You should compare with a bitcoind in initial block download.

Low. I don't see how these flags would make any significant difference to the CPU usage.

Sent from my Nokia phone -----Original Message----- From: Philip Kaufmann Sent: 20/05/2012 14:10:49 Subject: Re: [bitcoin] during block-chain download: high CPU load + GUI lags + addresses don't stay selected and lose focus (0.6.1 RC1) (#1154)

#1205 has improved the CPU usage during initial block download, but it feels still a bit hight. @laanwj How is CPU usage on Ubuntu with -debug -logtimestamps?

Reply to this email directly or view it on GitHub: #1154 (comment)