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Ethstore optimizations #6827

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merged 1 commit into from
Oct 20, 2017
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Ethstore optimizations #6827

merged 1 commit into from
Oct 20, 2017

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arkpar
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@arkpar arkpar commented Oct 19, 2017

Closes #6456, #6787

@arkpar arkpar added A0-pleasereview 🤓 Pull request needs code review. B0-patch M4-core ⛓ Core client code / Rust. labels Oct 19, 2017
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LGTM, minor nitpicks


fn last_modification_date(&self) -> Result<u64, Error> {
use std::time::UNIX_EPOCH;
let duration = fs::metadata(&self.path)?.modified()?.duration_since(UNIX_EPOCH).unwrap();
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expect?

return Ok(())
let mut last_timestamp = self.timestamp.lock();
let now = Instant::now();
if (now - last_timestamp.last_checked) > Duration::from_secs(REFRESH_TIME_SEC) {
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I would rather store last_timestamp.valid_till to avoid subtraction (and possible overflow in case the time is adjusted by the system):

if last_timestamp.valid_till < now {

}

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Instant is monotonic. It is not affected by clock changes and is guaranteed to be never decreased.

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Fair enough.

.cloned()
.ok_or(Error::InvalidAccount)
let cache = self.cache.read();
let mut r = cache.range((::std::collections::Bound::Included(*address), ::std::collections::Bound::Included(*address)));
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use ::std::collections::Bound at the top of the function?

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5chdn commented Oct 19, 2017

Is this related to #6456 and #6787?

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arkpar commented Oct 19, 2017

Right, closes #6456, #6787

@arkpar arkpar force-pushed the ethstore-optimize branch from 8d8a11a to 52e2adc Compare October 19, 2017 19:57
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This fixes the issue #6787 and is now finding/keeping peers.
However parity is using a massive amount of disk read IO...like 100% disk read IO all the time (using latest master branch + this commit)

let mut last_timestamp = self.timestamp.lock();
let now = Instant::now();
if (now - last_timestamp.last_checked) > Duration::from_secs(REFRESH_TIME_SEC) {
let dir_hash = Some(self.dir.unique_repr()?);

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This appears to be creating a disk IO read problem. Because every 5 seconds you end up looping and hashing all files in the keystore...if this is a large number of files (in my case 150,000)...in the end causes total server crash.

Is there a better way to detect changes in the keystore dir? Possibly only detect a change when new key is added via personal_newAccount... calls. Or simple file count?

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unique_repr is changed to return directory' last modification date in this PR. So no more hashing here

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@AdvancedStyle are you saying your server crashes with the changes from this PR?

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Yes, doing more testing and will provide more information shortly.

Basically once I compile/run latest master with this PR it fixes the peer connections, but then crashes the server (with noticeably huge amount of disk reading).

But i'll do a bit more testing and see if I can gather some actually error messages from the server crash

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Ok, i've been using iostat / iotop / tracefile (https://gitlab.com/ole.tange/tangetools/tree/master/tracefile) to montor disk IO and here are the results:

With using latest master the iostat util is quite low (less than 5%) however the tracefiles shows that parity is constantly accessing the keystore files...but it is not causing high disk util and not causing server crash..only causing peers to drop/timeout and syncing to stop.

After PR #6827 the iostat util goes through the roof (50-100% disk util all the time):

iostat output sample: avg-cpu: %user %nice %system %iowait %steal %idle 23.14 0.00 20.48 13.56 0.27 42.55

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
vda 0.00 0.00 5339.00 0.00 49176.00 0.00 18.42 0.75 0.14 0.14 0.00 0.09 49.60

avg-cpu: %user %nice %system %iowait %steal %idle
20.21 0.00 17.32 14.70 0.26 47.51

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
vda 0.00 17.00 5192.00 3.00 46776.00 80.00 18.04 0.74 0.14 0.14 2.67 0.11 55.60

avg-cpu: %user %nice %system %iowait %steal %idle
25.07 0.00 15.04 10.55 0.53 48.81

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
vda 0.00 28.00 4083.00 2.00 38940.00 120.00 19.12 0.60 0.15 0.15 2.00 0.10 42.40

avg-cpu: %user %nice %system %iowait %steal %idle
22.13 0.00 18.67 15.73 0.27 43.20

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
vda 0.00 10.00 3744.00 4.00 32000.00 56.00 17.11 0.83 0.22 0.21 1.00 0.17 64.00

avg-cpu: %user %nice %system %iowait %steal %idle
24.42 0.00 15.32 32.21 0.26 27.79

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
vda 0.00 13.00 2987.00 4.00 28780.00 68.00 19.29 2.07 0.70 0.70 1.00 0.27 80.80

But the strange thing is the tracefile (strace script) is not really seeing a lot of file access on the process (parity is no longer accessing the keystore files individuals)... it only appears to be accessing the keystore dir...so why all the disk IO?:

Sample of tracefile output:

/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484066.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484067.log
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484068.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484066.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484068.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484069.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484069.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484066.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484064.sst
/home/ethereum/.ethereum/keystore/ethereum
/home/ethereum/.ethereum/keystore/ethereum
/home/ethereum/.ethereum/keystore/ethereum
/home/ethereum/.ethereum/keystore/ethereum
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484070.log
/sys/devices/system/cpu/online
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484071.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484071.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484072.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484072.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484071.sst
/home/ethereum/.local/share/io.parity.ethereum/chains/ethereum/db/906a34e69aec8c0d/overlayrecent/db/484068.sst
/home/ethereum/.ethereum/keystore/ethereum
/home/ethereum/.ethereum/keystore/ethereum

VM then hangs / crashes after a few minutes with hung_task_timeout_secs

INFO: task kworker/[...] blocked for more than 120 seconds.
 Not tainted [...]
 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

And a bunch of similar hung tasks.

Conclusion:
For some reason the modified time check on the keystore dir might be creating a lot of IO read?

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I mean at first was testing with master (no IO read problem / no crash).

Then i compiled with this PR #6827 (git fetch origin pull/6827/head:sometest && git checkout sometest and compiled)

The IO read problem only occurred after compiling with PR #6827

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The IO must be just the database IO. Does the machine have HDD or SSD? How exactly does it crash? Is there a backtrace printed?

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SSD. Server running on a KVM virtual machine (Debian host, Ubuntu 16 guest).

The entire virtual machine just locks up; SSH non-responsive and virtmanager console non-responsive, then it dumps a series of error messages in the virtmanager console similar to:

INFO: task kworker/[...] blocked for more than 120 seconds.
Not tainted [...]
kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

Note, i'm running parity with params:

screen -d -m parity --cache-size 4096 --allow-ips public --jsonrpc-apis web3,eth,net,parity,traces,rpc,personal --geth --keys-path /home/ethereum/.ethereum/keystore

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I've decided to clone the VM and try to delete/resync the chain from 0 to see if that helps, and so far it seems to be doing ok (no IO read problems so far)...will post back shortly

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I have resynced the chain from 0 using PR #6827 and now disk IO is normal again and all is working.

So everything is fine now (fingers crossed).

The issue of slow key generation (issue #6839 is also fixed)

@svyatonik svyatonik added A8-looksgood 🦄 Pull request is reviewed well. and removed A0-pleasereview 🤓 Pull request needs code review. labels Oct 20, 2017
@arkpar arkpar merged commit 097815c into master Oct 20, 2017
@arkpar arkpar deleted the ethstore-optimize branch October 20, 2017 18:20
arkpar added a commit that referenced this pull request Oct 20, 2017
arkpar added a commit that referenced this pull request Oct 20, 2017
@AdvancedStyle AdvancedStyle mentioned this pull request Oct 21, 2017
lght pushed a commit to lght/parity that referenced this pull request Oct 25, 2017
@5chdn 5chdn added this to the 1.8 milestone Dec 8, 2017
tomusdrw pushed a commit that referenced this pull request Dec 20, 2017
5chdn pushed a commit that referenced this pull request Dec 27, 2017
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