DefaultTuple underestimate the memory footprint for string
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Key: PIG-1443
URL: https://issues.apache.org/jira/browse/PIG-1443
Project: Pig
Issue Type: Bug
Components: impl
Affects Versions: 0.7.0
Reporter: Daniel Dai
Assignee: Daniel Dai
Fix For: 0.8.0
Currently, in DefaultTuple, we estimate the memory footprint for string as if
it is char array. The formula we use is: length * 2 + 12. It turns out we
underestimate the memory usage for string. Here is a list of real memory
footprint for string we get from memory dump:
| length of string | memory in bytes |
| 7 | 56 |
| 3 | 48 |
| 1 | 40 |
I did a search and find the following formula can accurately estimate the
memory footprint for string:
{code}
8 * (int) (((length * 2) + 45) / 8)
{code}
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