mirror of https://github.com/lua/lua
Several tweaks in the garbage collector
- back with step size in collectgarbage("step") - adjustments in defaults for some GC parameters - adjustments in 'luaO_codeparam'
This commit is contained in:
parent
e81f586001
commit
12b6f610b0
18
lapi.c
18
lapi.c
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@ -416,10 +416,11 @@ LUA_API const char *lua_tolstring (lua_State *L, int idx, size_t *len) {
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luaC_checkGC(L);
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o = index2value(L, idx); /* previous call may reallocate the stack */
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}
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if (len != NULL)
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*len = tsslen(tsvalue(o));
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lua_unlock(L);
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return getstr(tsvalue(o));
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if (len != NULL)
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return getlstr(tsvalue(o), *len);
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else
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return getstr(tsvalue(o));
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}
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@ -1174,11 +1175,16 @@ LUA_API int lua_gc (lua_State *L, int what, ...) {
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}
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case LUA_GCSTEP: {
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lu_byte oldstp = g->gcstp;
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l_obj n = va_arg(argp, int);
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int work = 0; /* true if GC did some work */
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g->gcstp = 0; /* allow GC to run (other bits must be zero here) */
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luaC_step(L); /* run one basic step */
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g->gcstp = oldstp; /* restore previous state */
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if (g->gcstate == GCSpause) /* end of cycle? */
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if (n <= 0)
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n = g->GCdebt; /* force to run one basic step */
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luaE_setdebt(g, g->GCdebt - n);
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luaC_condGC(L, (void)0, work = 1);
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if (work && g->gcstate == GCSpause) /* end of cycle? */
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res = 1; /* signal it */
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g->gcstp = oldstp; /* restore previous state */
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break;
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}
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case LUA_GCISRUNNING: {
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10
lbaselib.c
10
lbaselib.c
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@ -213,7 +213,8 @@ static int luaB_collectgarbage (lua_State *L) {
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return 1;
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}
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case LUA_GCSTEP: {
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int res = lua_gc(L, o);
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lua_Integer n = luaL_optinteger(L, 2, 0);
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int res = lua_gc(L, o, (int)n);
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checkvalres(res);
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lua_pushboolean(L, res);
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return 1;
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@ -239,7 +240,7 @@ static int luaB_collectgarbage (lua_State *L) {
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LUA_GCPPAUSE, LUA_GCPSTEPMUL, LUA_GCPSTEPSIZE};
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int p = pnum[luaL_checkoption(L, 2, NULL, params)];
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lua_Integer value = luaL_checkinteger(L, 3);
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lua_pushinteger(L, lua_gc(L, o, p, value));
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lua_pushinteger(L, lua_gc(L, o, p, (int)value));
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return 1;
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}
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default: {
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@ -337,10 +338,7 @@ static int load_aux (lua_State *L, int status, int envidx) {
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static const char *getmode (lua_State *L, int idx) {
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const char *mode = luaL_optstring(L, idx, "bt");
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int i = 0;
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if (mode[i] == 'b') i++;
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if (mode[i] == 't') i++;
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if (mode[i] != '\0')
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if (strchr(mode, 'B') != NULL) /* Lua code cannot use fixed buffers */
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luaL_argerror(L, idx, "invalid mode");
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return mode;
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}
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4
lgc.h
4
lgc.h
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@ -171,13 +171,13 @@
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** Major collections will shift to minor ones after a collection
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** collects at least LUAI_MAJORMINOR% of the new objects.
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*/
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#define LUAI_MAJORMINOR 80
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#define LUAI_MAJORMINOR 50
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/*
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** A young (minor) collection will run after creating LUAI_GENMINORMUL%
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** new objects.
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*/
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#define LUAI_GENMINORMUL 20
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#define LUAI_GENMINORMUL 25
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/* incremental */
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18
lobject.c
18
lobject.c
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@ -50,22 +50,22 @@ int luaO_ceillog2 (unsigned int x) {
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}
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/*
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** Encodes 'p'% as a floating-point byte, represented as (eeeeexxx).
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** Encodes 'p'% as a floating-point byte, represented as (eeeexxxx).
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** The exponent is represented using excess-7. Mimicking IEEE 754, the
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** representation normalizes the number when possible, assuming an extra
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** 1 before the mantissa (xxx) and adding one to the exponent (eeeeexxx)
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** to signal that. So, the real value is (1xxx) * 2^(eeeee - 8) if
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** eeeee != 0, and (xxx) * 2^-7 otherwise.
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** 1 before the mantissa (xxxx) and adding one to the exponent (eeee)
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** to signal that. So, the real value is (1xxxx) * 2^(eeee - 7 - 1) if
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** eeee != 0, and (xxxx) * 2^-7 otherwise (subnormal numbers).
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*/
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unsigned int luaO_codeparam (unsigned int p) {
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if (p >= (cast(lu_mem, 0xF) << 0xF) / 128 * 100) /* overflow? */
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if (p >= (cast(lu_mem, 0x1F) << (0xF - 7 - 1)) * 100u) /* overflow? */
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return 0xFF; /* return maximum value */
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else {
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p = (p * 128u) / 100;
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if (p <= 0xF)
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return p;
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p = (cast(l_uint32, p) * 128 + 99) / 100; /* round up the division */
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if (p < 0x10) /* subnormal number? */
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return p; /* exponent bits are already zero; nothing else to do */
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else {
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int log = luaO_ceillog2(p + 1) - 5;
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int log = luaO_ceillog2(p + 1) - 5; /* preserve 5 bits */
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return ((p >> log) - 0x10) | ((log + 1) << 4);
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}
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}
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@ -427,8 +427,8 @@ typedef struct TString {
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** Get string and length */
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#define getlstr(ts, len) \
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(strisshr(ts) \
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? (cast_void(len = (ts)->shrlen), rawgetshrstr(ts)) \
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: (cast_void(len = (ts)->u.lnglen), (ts)->contents))
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? (cast_void((len) = (ts)->shrlen), rawgetshrstr(ts)) \
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: (cast_void((len) = (ts)->u.lnglen), (ts)->contents))
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/* }================================================================== */
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@ -666,18 +666,6 @@ A value of 200 means that the collector waits for
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the total number of objects to double before starting a new cycle.
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The default value is 300; the maximum value is 1000.
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The garbage-collector step multiplier
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controls the speed of the collector relative to
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object creation,
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that is,
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how many objects it marks or sweeps for each object created.
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Larger values make the collector more aggressive.
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Beware that values too small can
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make the collector too slow to ever finish a cycle.
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The default value is 200; the maximum value is 1000.
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As a special case, a zero value means unlimited work,
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effectively producing a non-incremental, stop-the-world collector.
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The garbage-collector step size controls the
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size of each incremental step,
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specifically how many objects the interpreter creates
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@ -686,6 +674,17 @@ A value of @M{n} means the interpreter will create
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approximately @M{n} objects between steps.
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The default value is 250.
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The garbage-collector step multiplier
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controls the size of each GC step.
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A value of @M{n} means the interpreter will mark or sweep,
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in each step, @M{n%} objects for each created object.
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Larger values make the collector more aggressive.
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Beware that values too small can
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make the collector too slow to ever finish a cycle.
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The default value is 200; the maximum value is 1000.
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As a special case, a zero value means unlimited work,
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effectively producing a non-incremental, stop-the-world collector.
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}
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@sect3{genmode| @title{Generational Garbage Collection}
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@ -707,11 +706,12 @@ and the @def{major-minor multiplier}.
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The minor multiplier controls the frequency of minor collections.
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For a minor multiplier @M{x},
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a new minor collection will be done when the number of objects
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grows @M{x%} larger than the number in use just after the last collection.
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grows @M{x%} larger than the number in use just
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after the last major collection.
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For instance, for a multiplier of 20,
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the collector will do a minor collection when the number of objects
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gets 20% larger than the total after the last major collection.
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The default value is 20.
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The default value is 25.
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The minor-major multiplier controls the shift to major collections.
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For a multiplier @M{x},
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@ -728,11 +728,10 @@ For a multiplier @M{x},
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the collector will shift back to minor collections
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after a major collection collects at least @M{x%}
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of the objects allocated during the last cycle.
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In particular, for a multiplier of 0,
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the collector will immediately shift back to minor collections
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after doing one cycle of major collections.
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The default value is 80.
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The default value is 50.
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}
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@ -3327,7 +3326,7 @@ Returns the remainder of dividing the current amount of bytes of
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memory in use by Lua by 1024.
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}
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@item{@defid{LUA_GCSTEP}|
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@item{@defid{LUA_GCSTEP} (int n)|
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Performs a step of garbage collection.
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}
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@ -3686,9 +3685,12 @@ Moreover, for a fixed buffer,
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the reader function should return the entire chunk in the first read.
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(As an example, @Lid{luaL_loadbufferx} does that.)
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@id{lua_load} uses the stack internally,
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so the reader function must always leave the stack
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unmodified when returning.
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The function @Lid{lua_load} fully preserves the Lua stack
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through the calls to the reader function,
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except that it may push some values for internal use
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before the first call,
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and it restores the stack size to its original size plus one
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(for the pushed result) after the last call.
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@id{lua_load} can return
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@Lid{LUA_OK}, @Lid{LUA_ERRSYNTAX}, or @Lid{LUA_ERRMEM}.
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@ -6344,13 +6346,24 @@ gives the exact number of bytes in use by Lua.
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@item{@St{step}|
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Performs a garbage-collection step.
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This option may be followed by an extra argument,
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an integer with the step size.
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The default for this argument is zero.
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If the size is a positive @id{n},
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the collector acts as if @id{n} new objects have been created.
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If the size is zero,
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the collector performs a basic step.
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In incremental mode,
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a basic step corresponds to the current step size.
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In generational mode,
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a basic step performs a full minor collection or
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a major collection,
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if the collector has scheduled one.
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In incremental mode,
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that step corresponds to the current step size;
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the function returns @true if the step finished a collection cycle.
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In generational mode,
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the step performs a full minor collection or
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a major collection,
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if the collector has scheduled one;
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the function returns @true if the step performed a major collection.
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}
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@ -6382,13 +6395,9 @@ The argument @id{param} must have one of the following values:
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@item{@St{stepmul}| The step multiplier. }
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@item{@St{stepsize}| The step size. }
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}
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To be able to divide by 100
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(as most parameters are given as percentages)
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without using floating-point arithmetic,
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Lua stores these parameters encoded.
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This encoding approximates the real value;
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Lua rounds these values before storing them;
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so, the value returned as the previous value may not be
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equal to the last value set.
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exactly the last value set.
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}
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}
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@ -74,6 +74,8 @@ io.input(io.stdin); io.output(io.stdout);
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os.remove(file)
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assert(not loadfile(file))
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-- Lua code cannot use chunks with fixed buffers
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checkerr("invalid mode", load, "", "", "B")
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checkerr("", dofile, file)
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assert(not io.open(file))
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io.output(file)
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@ -35,7 +35,7 @@ do
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collectgarbage("setparam", "pause", t[i])
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for j = 1, #t do
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collectgarbage("setparam", "stepmul", t[j])
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collectgarbage("step")
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collectgarbage("step", t[j])
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end
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end
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-- restore original parameters
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@ -45,6 +45,33 @@ do
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end
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--
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-- test the "size" of basic GC steps (whatever they mean...)
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--
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do print("steps")
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local function dosteps (siz)
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collectgarbage()
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local a = {}
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for i=1,100 do a[i] = {{}}; local b = {} end
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local x = gcinfo()
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local i = 0
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repeat -- do steps until it completes a collection cycle
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i = i+1
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until collectgarbage("step", siz)
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assert(gcinfo() < x)
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return i -- number of steps
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end
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collectgarbage"stop"
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if not _port then
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assert(dosteps(10) < dosteps(2))
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end
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end
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_G["while"] = 234
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