Well, I haven't though about this in a while, but the 8ms point only holds if the disk write buffer is turned off, no? Otherwise, the disk will be able to do a better job with scheduling the writes.
-Flavio On Friday, October 17, 2014 4:46 PM, Ivan Kelly <[email protected]> wrote: > > >Are you running this on SSD? 2941 seems like a lot, given that for >each write you need to fsync to disk, which takes at least 8ms. > >On 17 October 2014 17:42, Ivan Kelly <[email protected]> wrote: >> Are you running this on SSD? 2941 seems like a lot, given that for >> each write you need to fsync to disk, which takes at least 8ms. >> >> On 17 October 2014 17:28, sky_cord <[email protected]> wrote: >>> Thanks for your help. >>> After adding the two config items into bk_server.conf : >>> >>> journalFlushWhenQueueEmpty=true >>> journalMaxGroupWaitMSec=0 >>> >>> The write speed rise up to 800-900 entries per second in one ledger, length >>> of each entry is 50 bytes. >>> >>> But it's still lower than I expected（The sync write speed is 2941 entries/s >>> based onbookkeepr-4.2.2）. >>> >>> Could you describe your test result? And Is there any way to improve write >>> performance ? >>> >>> Thank you. >>> >>> >>> >>> >>> At 2014-10-17 20:13:07, "Ivan Kelly" <[email protected]> wrote: >>>>Ah, I know what this is. Twitter added some changes that makes write >>>>throughput much higher when there's a high write rate. In this case >>>>the latency for a single writes goes go up though (as it's doing more >>>>buffering on the journal). Try setting: >>>> >>>>journalFlushWhenQueueEmpty=true >>>>journalMaxGroupWaitMSec=0 >>>> >>>>in bk_server.conf >>>> >>>> >>>>Also, the journal and ledger directories are on the same disk. This >>>>will have a detrimental affect once the write buffers start flushing. >>>>We always recommend that you put the journal on its own independent >>>>disk. >>>> >>>>The reads are fast because it doesn't need to hit disk, as there's not >>>>much data that has been written. >>>> >>>>-Ivan >>>> >>>>On 17 October 2014 13:32, [email protected] <[email protected]> wrote: >>>>> The write speed of bookkeper that version less than 4.30 is bigger than >>>>> 1200 >>>>> entries per second when i use the same test code >>>>> >>>>> ________________________________ >>>>> [email protected] >>>>> >>>>> >>>>> From: Jiannan Wang >>>>> Date: 2014-10-17 18:31 >>>>> To: [email protected] >>>>> CC: [email protected] >>>>> Subject: Re: hi, why write speed of bookkeeper-4.3.0 is very slow? >>>>> Could you share more information: >>>>> - What's the number of write_num? >>>>> - What's the read throughput under your test? >>>>> - Does the 5 bookie servers run in same machine? >>>>> - Could you check whether StringUtil.div works well? >>>>> - Could you also try async write API and tell us the output? >>>>> >>>>> Regards, >>>>> Jiannan >>>>> >>>>> From: "[email protected]" <[email protected]> >>>>> Reply-To: "[email protected]" >>>>> <[email protected]> >>>>> Date: Friday, October 17, 2014 at 3:38 PM >>>>> To: bookkeeper-user <[email protected]> >>>>> Subject: hi, why write speed of bookkeeper-4.3.0 is very slow? >>>>> >>>>> hi, >>>>> I have tried bookkeeper-4.3.0 today. But its write speed is 4 >>>>> entries >>>>> per sec in my environment. >>>>> There are 5 bookkeeper-server-4.3.0 in my env. >>>>> Is there anything wrong? Test codes as follows: >>>>> public void syncWriteLedger(long write_num) throws InterruptedException, >>>>> BKException { >>>>> byte[] pwd = "foobar".getBytes(); >>>>> LedgerHandle lh = client.createLedger(3, 2, >>>>> DigestType.MAC, pwd); >>>>> >>>>> long ledgerId = lh.getId(); >>>>> System.out.println("ledgerId=" + ledgerId); >>>>> System.out >>>>> .println("data_len=" >>>>> + ("Hello World!afdafdafdfxtyb457u8n9,7.,pbesgcerfqx" + write_num) >>>>> .getBytes().length); >>>>> byte[] data = ("Hello World!afdafdafdfxtyb457u8n9,7.,pbesgcerfqx" + >>>>> write_num).getBytes(); >>>>> long st = System.currentTimeMillis(); >>>>> for (int i = 0; i < write_num; i++) { >>>>> lh.addEntry(data); >>>>> } >>>>> long ut = System.currentTimeMillis() - st; >>>>> lh.close(); >>>>> double uts = StringUtil.div(ut, 1000, 3); >>>>> double wspeed = StringUtil.div(write_num, uts, 2); >>>>> System.out.println("ut=" + ut + " ms, write_num=" + write_num >>>>> + ", write speed=" + wspeed + "/s"); >>>>> >>>>> >>>>> LedgerHandle lh2 = client.openLedger(ledgerId, BookKeeper.DigestType.MAC, >>>>> pwd); >>>>> long lastEntry = lh2.getLastAddConfirmed(); >>>>> st = System.currentTimeMillis(); >>>>> Enumeration<LedgerEntry> entries = lh2.readEntries(0, lastEntry); >>>>> while (entries.hasMoreElements()) { >>>>> byte[] bytes = entries.nextElement().getEntry(); >>>>> System.out.println(new String(bytes)); >>>>> } >>>>> ut = System.currentTimeMillis() - st; >>>>> lh2.close(); >>>>> uts = StringUtil.div(ut, 1000, 3); >>>>> double rspeed = StringUtil.div(write_num, uts, 2); >>>>> System.out.println("ut=" + ut + " ms, read_num=" + write_num >>>>> + ", read speed=" + rspeed + "/s"); >>>>> >>>>> } >>>>> ________________________________ >>>>> [email protected] >>> >>> >>> > >
