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-rw-r--r--src/xz/coder.c63
1 files changed, 43 insertions, 20 deletions
diff --git a/src/xz/coder.c b/src/xz/coder.c
index b5f7c392..268359a4 100644
--- a/src/xz/coder.c
+++ b/src/xz/coder.c
@@ -269,10 +269,9 @@ coder_set_compression_settings(void)
if (memory_usage <= memory_limit)
return;
- // If --no-adjust was used or we didn't find LZMA1 or
- // LZMA2 as the last filter, give an error immediately.
- // --format=raw implies --no-adjust.
- if (!opt_auto_adjust || opt_format == FORMAT_RAW)
+ // With --format=raw settings are never adjusted to meet
+ // the memory usage limit.
+ if (opt_format == FORMAT_RAW)
memlimit_too_small(memory_usage);
assert(opt_mode == MODE_COMPRESS);
@@ -282,34 +281,58 @@ coder_set_compression_settings(void)
if (opt_format == FORMAT_XZ && mt_options.threads > 1) {
// Try to reduce the number of threads before
// adjusting the compression settings down.
- do {
- // FIXME? The real single-threaded mode has
- // lower memory usage, but it's not comparable
- // because it doesn't write the size info
- // into Block Headers.
- if (--mt_options.threads == 0)
- memlimit_too_small(memory_usage);
-
+ while (mt_options.threads > 1) {
+ // Reduce the number of threads by one and check
+ // the memory usage.
+ --mt_options.threads;
memory_usage = lzma_stream_encoder_mt_memusage(
&mt_options);
if (memory_usage == UINT64_MAX)
message_bug();
- } while (memory_usage > memory_limit);
+ if (memory_usage <= memory_limit) {
+ // The memory usage is now low enough.
+ message(V_WARNING, _("Reduced the number of "
+ "threads from %s to %s to not exceed "
+ "the memory usage limit of %s MiB"),
+ uint64_to_str(
+ hardware_threads_get(), 0),
+ uint64_to_str(mt_options.threads, 1),
+ uint64_to_str(round_up_to_mib(
+ memory_limit), 2));
+ return;
+ }
+ }
+
+ // If --no-adjust was used, we cannot drop to single-threaded
+ // mode since it produces different compressed output.
+ //
+ // NOTE: In xz 5.2.x, --no-adjust also prevented reducing
+ // the number of threads. This changed in 5.3.3alpha.
+ if (!opt_auto_adjust)
+ memlimit_too_small(memory_usage);
+
+ // Switch to single-threaded mode. It uses
+ // less memory than using one thread in
+ // the multithreaded mode but the output
+ // is also different.
+ hardware_threads_set(1);
+ memory_usage = lzma_raw_encoder_memusage(filters);
+ message(V_WARNING, _("Switching to single-threaded mode "
+ "to not exceed the memory usage limit of %s MiB"),
+ uint64_to_str(round_up_to_mib(memory_limit), 0));
- message(V_WARNING, _("Adjusted the number of threads "
- "from %s to %s to not exceed "
- "the memory usage limit of %s MiB"),
- uint64_to_str(hardware_threads_get(), 0),
- uint64_to_str(mt_options.threads, 1),
- uint64_to_str(round_up_to_mib(
- memory_limit), 2));
}
# endif
if (memory_usage <= memory_limit)
return;
+ // Don't adjust LZMA2 or LZMA1 dictionary size if --no-adjust
+ // was specified as that would change the compressed output.
+ if (!opt_auto_adjust)
+ memlimit_too_small(memory_usage);
+
// Look for the last filter if it is LZMA2 or LZMA1, so we can make
// it use less RAM. With other filters we don't know what to do.
size_t i = 0;