On Saturday, 20 December 2014 at 22:11:35 UTC, Xinok wrote:
(2) Furthermore, we need to improve the performance of the
garbage collector.
"Performance" is a complex issue in the case of GCs. There is not
"highest performance GC", only GCs optimally tuned for certain
scenarios. While a simple, imprecise, mark-and-sweep collector
like the one used by D right now is not that complicated, modern,
industrial GCs are very complex.
There are many decisions to be made and there is no single
"right" answer.
At this point I would like to quote a post about the evolution of
the Go garbage collector because Go originally had a primitive GC
too but is now far head of D's by any standard:
Plans for Go 1.4+ garbage collector:
hybrid stop-the-world/concurrent collector
stop-the-world part limited by a 10ms deadline
CPU cores dedicated to running the concurrent collector
tri-color mark-and-sweep algorithm
non-generational
non-compacting
fully precise
incurs a small cost if the program is moving pointers around
lower latency, but most likely also lower throughput, than Go
1.3 GC
Go 1.3 garbage collector updates on top of Go 1.1:
concurrent sweep (results in smaller pause times)
fully precise
Go 1.1 garbage collector:
mark-and-sweep (parallel implementation)
non-generational
non-compacting
mostly precise (except stack frames)
stop-the-world
bitmap-based representation
zero-cost when the program is not allocating memory (that is:
shuffling pointers around is as fast as in C, although in
practice this runs somewhat slower than C because the Go compiler
is not as advanced as C compilers such as GCC)
supports finalizers on objects
there is no support for weak references
Go 1.0 garbage collector:
same as Go 1.1, but instead of being mostly precise the
garbage collector is conservative. The conservative GC is able to
ignore objects such as []byte.
Replacing the GC with a different one is controversial, for
example:
except for very large heaps, it is unclear whether a
generational GC would be faster overall
package "unsafe" makes it hard to implement fully precise GC
and compacting GC
