Hi, Looks like: - "size" is a difference between retention size of cache before and after test. - "avgItemSize" is just "size/count"
So, avgItemSize also includes key and value size. Assume, we have 64-bit JVM with compressed oops, so links has 4 bytes overhead and there is 8 bytes alignment. Key size - 8 (long) ~ 24 (as wrapped Long object with aligment). Value size - 12 (obj header) +8(long) +8(long) + 4(ref to String) + 4(int) ~ 40 (with 8 byte alignment) Value String field size - 12 (obj header) + 4(hash) + 4(ref to char[]) + ~ 24 (with 8 byte alignment) Char array - 12 (obj header) + 4 (size) + 2*17 (chars) ~ 56 (with 8 byte alignment) Total value size: 120 bytes Total overhead: ~ 147 bytes + (primary index for sql) - (Hashmap buckets size). On Fri, Jun 30, 2017 at 9:56 PM, Pascal <[email protected]> wrote: > Hi Andrew, > > I measured this on 2.0. > size= 0MB count=64 avgItemSize=7431 > size= 0MB count=128 avgItemSize=3852 > size= 0MB count=256 avgItemSize=2061 > size= 0MB count=512 avgItemSize=1164 > size= 0MB count=1024 avgItemSize=716 > size= 0MB count=2048 avgItemSize=492 > size= 1MB count=4096 avgItemSize=380 > size= 2MB count=8192 avgItemSize=324 > size= 4MB count=16384 avgItemSize=303 > size= 8MB count=32768 avgItemSize=286 > size= 17MB count=65536 avgItemSize=284 > size= 34MB count=131072 avgItemSize=277 > size= 69MB count=262144 avgItemSize=276 > size= 137MB count=524288 avgItemSize=275 > size= 279MB count=1048576 avgItemSize=279 > size= 551MB count=2097152 avgItemSize=275 > size= 1103MB count=4194304 avgItemSize=275 > I assume the amount of unsued free space is negligible with caches bigger > than +/- 32MB. Correct? > > Pascal > > > > -- > View this message in context: http://apache-ignite-users. > 70518.x6.nabble.com/Measuring-cache-size-and-performance- > tp14072p14187.html > Sent from the Apache Ignite Users mailing list archive at Nabble.com. > -- Best regards, Andrey V. Mashenkov
