Summary:
With https://github.com/facebook/rocksdb/issues/11150 this becomes a practical change that I think is overall good for developer efficiency.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11168
Test Plan:
More efficient build of all unit tests and tools:
```
$ git clean -fdx
$ du -sh .
522M .
$ /usr/bin/time make -j32 LIB_MODE=static
...
14270.63user 1043.33system 11:19.85elapsed 2252%CPU (0avgtext+0avgdata 1929944maxresident)k
...
$ du -sh .
62G .
$
```
Vs.
```
$ git clean -fdx
$ du -sh .
522M .
$ /usr/bin/time make -j32 LIB_MODE=shared
...
9479.87user 478.26system 7:20.82elapsed 2258%CPU (0avgtext+0avgdata 1929272maxresident)k
...
$ du -sh .
5.4G .
$
```
So 1/3 less build time and >90% less space usage.
Individual unit test edit-compile-run is not too different. Modifying an average unit test source file:
```
$ touch db/version_builder_test.cc
$ /usr/bin/time make -j32 LIB_MODE=static version_builder_test
...
34.74user 3.37system 0:38.29elapsed 99%CPU (0avgtext+0avgdata 945520maxresident)k
```
Vs.
```
$ touch db/version_builder_test.cc
$ /usr/bin/time make -j32 LIB_MODE=shared version_builder_test
...
116.26user 43.91system 0:28.65elapsed 559%CPU (0avgtext+0avgdata 675160maxresident)k
```
A little faster with shared.
However, modifying an average DB implementation file has an extra linking step with shared lib:
```
$ touch db/db_impl/db_impl_files.cc
$ /usr/bin/time make -j32 LIB_MODE=static version_builder_test
...
33.17user 5.13system 0:39.70elapsed 96%CPU (0avgtext+0avgdata 945544maxresident)k
```
Vs.
```
$ touch db/db_impl/db_impl_files.cc
$ /usr/bin/time make -j32 LIB_MODE=shared version_builder_test
...
40.80user 4.66system 0:45.54elapsed 99%CPU (0avgtext+0avgdata 1056340maxresident)k
```
A little slower with shared.
On the whole, should be faster and lighter weight because of the many unit test files case
Reviewed By: cbi42
Differential Revision: D42894004
Pulled By: pdillinger
fbshipit-source-id: 9e827e52ace79b86f849b6a24466e318b4b605a7
Peter Dillinger
cf756ed916