Faster rebuild with GNU gold linker

Ioi Lam ioi.lam at
Wed Feb 20 01:01:47 UTC 2019

For the impatient engineers ....

I did some measurement between the default GNU linker "ld" vs "". 
I am trying to get the fastest rebuild time after I modify one cpp file. 
With gold, it's down to about 1/3 of the original time.

slowdebug (~220MB

                  recompile 1 cpp file  |  relink only
ld:                   33 s                   25 s
gold 1 thread:        16 s                    9 s
gold 8 threads:       13 s                    6 s

fastdebug (~360MB

                  recompile 1 cpp file  |  relink only
ld:                   35 s                    25 s
gold 1 thread:        18 s                    10 s
gold 8 threads:       15 s                     6 s

Question: do we want to add built-in support for gold into the JDK 


To choose gold, run configure with something like:

     --with-extra-ldflags='-fuse-ld=gold -Wl,--threads,--thread-count,8'

I essentially do a "make hotspot" and then move the into a JDK 
image, instead of doing a full JDK image build.

"make hotspot" makes a copy of (from 
support/modules_libs/java.base/server/ to jdk/lib/server/). I hacked the 
Makefile to make a hard link instead to avoid the unnecessary I/O. is built with --with-native-debug-symbols=internal to avoid 
the expensive invocations of objcopy and strip.

My environment:

I am using gcc7.3.0 on Ubuntu 16.04.5 on a 5 year old Dell Precision 
T7600 with dual socket Xeon E5-2665 @ 2.40GHz, 64GB RAM, Samsung 840 PRO 
SSD. I suspect gold can run even faster, but my slow SSD is holding it back.

ld version   = GNU ld (GNU Binutils) 2.30
gold version = GNU gold (GNU Binutils for Ubuntu 2.26.1) 1.11

(These are just the versions available to me on my machine, not 
necessarily the best)

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