On 08/11/2016 02:34 PM, Ali Çehreli wrote:
> the application may be calling exit() itself,
> where it could have made a call to get the profile information. The main
> issue here is that the output of GC profile information is hardwired to
> GC destruction (and stdout).
Instead of coming up with a design and fixing druntime, for now I hacked
it by
1) Declaring druntime's profiling variables with their mangled names
2) Copying and modifying the druntime code that dumps stats so that it
accepts any FILE*
Sorry to dump this code here but maybe others will need it as well. The
program must be started by turning GC profiling on:
$ ./foo "--DRT-gcopt=profile:1"
(See https://dlang.org/spec/garbage.html#gc_config )
Ali
/* HACK: A helper mixin that converts pairs of types and symbols to
their corresponding declarations accessible from
druntime. For example, the following definition is produced for the
pair of (int, "i"):
extern(C) pragma(mangle, mangle!int("gc.gc.i")) extern __gshared int i;
*/
mixin template declareGCProfVars(A...) {
string definitions() {
string result;
string currentType;
/* static */ foreach(i, a; A) {
static if ((i % 2) == 0) {
static assert(is(a), "Expected a type, not " ~ a.stringof);
currentType = a.stringof; // Save for the next iteration
}
else {
static assert (is(typeof(a) == string), "Expected
string, not " ~ a.stringof);
result ~= `extern(C) pragma(mangle, mangle!` ~
currentType ~ `("gc.gc.`
~ a ~ `")) extern __gshared ` ~ currentType ~
` ` ~ a ~ `;`;
currentType = ""; // play safe
}
}
return result;
}
import core.demangle;
mixin (definitions());
}
/* List of GC profiling variables that druntime uses as of 2.071. Copied
from src/gc/impl/conservative/gc.d of
* https://github.com/dlang/druntime */
import std.datetime : Duration;
mixin declareGCProfVars!(
Duration, "prepTime",
Duration, "markTime",
Duration, "sweepTime",
Duration, "recoverTime",
Duration, "maxPauseTime",
size_t, "numCollections",
size_t, "maxPoolMemory",
);
public import std.stdio : FILE;
void dumpGCProfile(FILE *file) {
import std.stdio : fprintf;
/* Adapted from src/gc/impl/conservative/gc.d of
https://github.com/dlang/druntime */
fprintf(file, "\tNumber of collections: %llu\n",
cast(ulong)numCollections);
fprintf(file, "\tTotal GC prep time: %lld milliseconds\n",
prepTime.total!("msecs"));
fprintf(file, "\tTotal mark time: %lld milliseconds\n",
markTime.total!("msecs"));
fprintf(file, "\tTotal sweep time: %lld milliseconds\n",
sweepTime.total!("msecs"));
fprintf(file, "\tTotal page recovery time: %lld milliseconds\n",
recoverTime.total!("msecs"));
const long maxPause = maxPauseTime.total!("msecs");
fprintf(file, "\tMax Pause Time: %lld milliseconds\n", maxPause);
const long gcTime = (recoverTime + sweepTime + markTime +
prepTime).total!("msecs");
fprintf(file, "\tGrand total GC time: %lld milliseconds\n", gcTime);
const long pauseTime = (markTime + prepTime).total!("msecs");
fprintf(file, "GC summary:%5lld MB,%5lld GC%5lld ms, Pauses%5lld ms
<%5lld ms\n",
cast(long) maxPoolMemory >> 20, cast(ulong)numCollections,
gcTime,
pauseTime, maxPause);
}
bool isGCProfOn() {
import core.runtime : Runtime;
import std.regex : ctRegex, match;
import std.algorithm : any;
/* Although the GC documentation says that the program arguments
"are still available via rt_args"[1], they seem to
* be available only through Runtime.args().
*
* [1] https://dlang.org/spec/garbage.html#gc_config
*/
enum r = ctRegex!"--DRT-gcopt.*profile:1";
return Runtime.args().any!(arg => arg.match(r));
}
import std.range;
import std.algorithm;
import std.stdio;
import core.stdc.stdlib;
void main() {
// Cause some allocations
size_t total;
iota(1000).each!(i => total += iota(1000).map!(j => new
int[10000]).array.length);
writeln(total);
/* Let's assume that the program is about to exit() but we're still
interested in GC stats. First ensure that the
* stats are requested on the command line. */
if (isGCProfOn()) {
dumpGCProfile(stderr.getFP());
}
exit(0);
}
