On Saturday, 27 June 2020 at 14:12:09 UTC, kinke wrote:
On Saturday, 27 June 2020 at 10:08:15 UTC, James Gray wrote:
have run into a memory leak
Something seems really off indeed. I've run this on Win64 with
DMD (2.092) and LDC (1.22), without any extra cmdline options:
-----
import core.memory;
import core.stdc.stdio;
import std.range;
import std.format;
auto f(R)(R r) { return format("%s", r); }
int toMB(ulong size) { return cast(int) (size / 1048576.0 +
0.5); }
void printGCStats()
{
const stats = GC.stats;
const used = toMB(stats.usedSize);
const free = toMB(stats.freeSize);
const total = toMB(stats.usedSize + stats.freeSize);
printf(" GC stats: %dM used, %dM free, %dM total\n", used,
free, total);
}
void main()
{
printGCStats();
while (true)
{
puts("Starting");
string str = f(iota(100_000_000));
printf(" string size: %dM\n", toMB(str.length));
str = null;
GC.collect();
printGCStats();
}
}
-----
Output with DMD (no change with the precise GC via
`--DRT-gcopt=gc:precise`):
-----
GC stats: 0M used, 1M free, 1M total
Starting
string size: 943M
GC stats: 1168M used, 1139M free, 2306M total
Starting
string size: 943M
GC stats: 1168M used, 2456M free, 3623M total
Starting
string size: 943M
GC stats: 1168M used, 2456M free, 3623M total
Starting
string size: 943M
GC stats: 1168M used, 2456M free, 3623M total
Starting
string size: 943M
GC stats: 1168M used, 2456M free, 3623M total
-----
With LDC:
-----
GC stats: 0M used, 1M free, 1M total
Starting
string size: 943M
GC stats: 1168M used, 1139M free, 2306M total
Starting
string size: 943M
GC stats: 2335M used, 1288M free, 3623M total
Starting
string size: 943M
GC stats: 2335M used, 2605M free, 4940M total
Starting
string size: 943M
GC stats: 2335M used, 2605M free, 4940M total
Starting
string size: 943M
GC stats: 2335M used, 2605M free, 4940M total
-----
Note that I explicitly clear the `str` slice before
GC.collect(), so that the stack shouldn't contain any refs to
the fat string anymore.
Thank you for doing this. I hope my example doesn't obscure what
you show here.
(I borrowed some of your code).
I have produced something which essentially reproduces my problem.
-----------
import std.range;
import std.algorithm;
import std.format;
import std.stdio;
import core.thread;
import core.memory;
struct Node {
Node* next;
Node* prev;
ulong val;
}
Node* insertAfter(Node* cur, ulong val) {
Node* node = new Node;
if (cur != null) {
node.next = cur.next;
node.prev = cur;
cur.next = node;
node.next.prev = node;
}
else {
node.next = node;
node.prev = node;
}
node.val = val;
return node;
}
int toMB(ulong size) { return cast(int) (size / 1048576.0 + 0.5);
}
void printGCStats()
{
const stats = GC.stats;
const used = toMB(stats.usedSize);
const free = toMB(stats.freeSize);
const total = toMB(stats.usedSize + stats.freeSize);
writef(" GC stats: %dM used, %dM free, %dM total\n", used,
free, total);
}
void main()
{
while(true)
{
printGCStats();
writeln("Starting");
Node* dll;
dll = iota(200000000).fold!((c,x)=>insertAfter(c,x))(dll);
writef("Last element %s\n", dll.val);
dll = null;
writeln("Done");
GC.collect();
GC.minimize();
Thread.sleep( dur!("msecs")( 10000 ) );
}
}
----------
With DMD this produces:
GC stats: 0M used, 0M free, 0M total
Starting
Last element 199999999
Done
GC stats: 6104M used, 51M free, 6155M total
Starting
Last element 199999999
Done
GC stats: 12207M used, 28M free, 12235M total
With LDC2 this produces:
GC stats: 0M used, 0M free, 0M total
Starting
Last element 199999999
Done
GC stats: 6104M used, 51M free, 6155M total
Starting
Last element 199999999
Done
GC stats: 12207M used, 28M free, 12235M total
