From: Derrick Stolee <dstolee@xxxxxxxxxxxxx> When repacking during the 'pack-files' job, we use the --batch-size option in 'git multi-pack-index repack'. The initial setting used --batch-size=0 to repack everything into a single pack-file. This is not sustaintable for a large repository. The amount of work required is also likely to use too many system resources for a background job. Update the 'git run-job pack-files' command by allowing a direct --batch-size option that can change the value provided. Update the default of "0" to a computed size based on the existing pack-files. While computing that new size, count the existing pack-files and skip the repack step if there are at most two pack-files. The dynamic default size is computed with this idea in mind for a client repository that was cloned from a very large remote: there is likely one "big" pack-file that was created at clone time. Thus, do not try repacking it as it is likely packed efficiently by the server. Instead, try packing the other pack-files into a single pack-file. The size is then computed as follows: batch size = total size - max pack size The batch size is then also limited to be at most two gigabytes. This serves two purposes. First, having a limit prevents doing too much work when the repository is extremely large. Pack-files larger than two gigabytes are likely to either contain large blobs or have been carefully repacked by a previous repack operation. Second, two gigabytes is the size limit for a signed 32-bit int. It's a good limit to consider, and to keep it far away from the unsigned 32-bit int limit. This limit comes to mind because on Windows an "unsigned long" is 32 bits and OPT_MAGNITUDE() uses unsigned longs for its parsing logic. This calculation mimics a similar calculation in Scalar [1], except for a 3% drop in the calculated batch size due to the round-off error that can happen with the "expected size" calculation for a pack-file. [1] https://github.com/microsoft/scalar/blob/616e9b16dd120b8fdb652d6d5a55618c731a8aea/Scalar.Common/Maintenance/PackfileMaintenanceStep.cs#L141-L143 Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx> --- Documentation/git-run-job.txt | 13 +++-- builtin/run-job.c | 90 ++++++++++++++++++++++++++++++++--- t/t7900-run-job.sh | 6 ++- 3 files changed, 96 insertions(+), 13 deletions(-) diff --git a/Documentation/git-run-job.txt b/Documentation/git-run-job.txt index 108ed25b8bd..cdd6417f7c9 100644 --- a/Documentation/git-run-job.txt +++ b/Documentation/git-run-job.txt @@ -9,7 +9,7 @@ git-run-job - Run a maintenance job. Intended for background operation. SYNOPSIS -------- [verse] -'git run-job (commit-graph|fetch|loose-objects|pack-files)' +'git run-job (commit-graph|fetch|loose-objects|pack-files) [<options>]' DESCRIPTION @@ -82,9 +82,14 @@ only happens if all objects in the pack-file are also stored in a newer pack-file. Second, it selects a group of pack-files whose "expected size" is below the batch size until the group has total expected size at least the batch size; see the `--batch-size` option for the `repack` -subcommand in linkgit:git-multi-pack-index[1]. The default batch-size is -zero, which is a special case that attempts to repack all pack-files -into a single pack-file. +subcommand in linkgit:git-multi-pack-index[1]. ++ +The default batch size is computed to optimize for having a single large +pack-file and many small pack-files. When there are two or fewer +pack-files, the job does not attempt to repack. Otherwise, the batch +size is the sum of all pack-file sizes minus the largest pack-file size. +The batch size is capped at two gigabytes. This intends to pack all +small pack-files into a single pack-file. GIT diff --git a/builtin/run-job.c b/builtin/run-job.c index d3543f7ccb9..2ccc3bbae2d 100644 --- a/builtin/run-job.c +++ b/builtin/run-job.c @@ -3,12 +3,18 @@ #include "commit-graph.h" #include "midx.h" #include "object-store.h" +#include "packfile.h" #include "parse-options.h" #include "repository.h" #include "run-command.h" static char const * const builtin_run_job_usage[] = { - N_("git run-job (commit-graph|fetch|loose-objects|pack-files)"), + N_("git run-job (commit-graph|fetch|loose-objects|pack-files) [<options>]"), + NULL +}; + +static char const * const builtin_run_job_pack_file_usage[] = { + N_("git run-job pack-files [--batch-size=<size>]"), NULL }; @@ -278,15 +284,74 @@ static int multi_pack_index_expire(void) return run_command_v_opt(cmd.argv, RUN_GIT_CMD); } -static int multi_pack_index_repack(void) +#define TWO_GIGABYTES (2147483647) + +static off_t get_auto_pack_size(int *count) +{ + /* + * The "auto" value is special: we optimize for + * one large pack-file (i.e. from a clone) and + * expect the rest to be small and they can be + * repacked quickly. Find the sum of the sizes + * other than the largest pack-file, then use + * that as the batch size. + */ + off_t total_size = 0; + off_t max_size = 0; + off_t result_size; + struct packed_git *p; + + *count = 0; + + reprepare_packed_git(the_repository); + for (p = get_all_packs(the_repository); p; p = p->next) { + (*count)++; + total_size += p->pack_size; + + if (p->pack_size > max_size) + max_size = p->pack_size; + } + + result_size = total_size - max_size; + + /* But limit ourselves to a batch size of 2g */ + if (result_size > TWO_GIGABYTES) + result_size = TWO_GIGABYTES; + + return result_size; +} + +#define UNSET_BATCH_SIZE ((unsigned long)-1) +static int multi_pack_index_repack(unsigned long batch_size) { int result; struct argv_array cmd = ARGV_ARRAY_INIT; + struct strbuf batch_arg = STRBUF_INIT; + int count; + off_t default_size = get_auto_pack_size(&count); + + if (count <= 2) + return 0; + + strbuf_addstr(&batch_arg, "--batch-size="); + + if (batch_size != UNSET_BATCH_SIZE) + strbuf_addf(&batch_arg, "\"%"PRIuMAX"\"", (uintmax_t)batch_size); + else + strbuf_addf(&batch_arg, "%"PRIuMAX, + (uintmax_t)default_size); + argv_array_pushl(&cmd, "multi-pack-index", "repack", - "--no-progress", "--batch-size=0", NULL); + "--no-progress", batch_arg.buf, NULL); result = run_command_v_opt(cmd.argv, RUN_GIT_CMD); - if (result && multi_pack_index_verify()) { + strbuf_release(&batch_arg); + + /* + * Verify here to avoid verifying again when there are two + * or fewer pack-files. + */ + if (!result && multi_pack_index_verify()) { warning(_("multi-pack-index verify failed after repack")); result = rewrite_multi_pack_index(); } @@ -294,8 +359,19 @@ static int multi_pack_index_repack(void) return result; } -static int run_pack_files_job(void) +static int run_pack_files_job(int argc, const char **argv) { + static unsigned long batch_size = UNSET_BATCH_SIZE; + static struct option builtin_run_job_pack_file_options[] = { + OPT_MAGNITUDE(0, "batch-size", &batch_size, + N_("specify a batch-size for the incremental repack")), + OPT_END(), + }; + + argc = parse_options(argc, argv, NULL, + builtin_run_job_pack_file_options, + builtin_run_job_pack_file_usage, 0); + if (multi_pack_index_write()) { error(_("failed to write multi-pack-index")); return 1; @@ -316,7 +392,7 @@ static int run_pack_files_job(void) return rewrite_multi_pack_index(); } - if (multi_pack_index_repack()) { + if (multi_pack_index_repack(batch_size)) { error(_("multi-pack-index repack failed")); return 1; } @@ -348,7 +424,7 @@ int cmd_run_job(int argc, const char **argv, const char *prefix) if (!strcmp(argv[0], "loose-objects")) return run_loose_objects_job(); if (!strcmp(argv[0], "pack-files")) - return run_pack_files_job(); + return run_pack_files_job(argc, argv); } usage_with_options(builtin_run_job_usage, diff --git a/t/t7900-run-job.sh b/t/t7900-run-job.sh index 416ba04989d..2d9f6cdf328 100755 --- a/t/t7900-run-job.sh +++ b/t/t7900-run-job.sh @@ -128,8 +128,10 @@ test_expect_success 'pack-files job' ' # the job deletes the two old packs, and does not write # a new one because only one pack remains. git -C client run-job pack-files && - ls client/.git/objects/pack/*.pack >packs-after && - test_line_count = 1 packs-after + ls client/$packDir/*.pack >packs-after && + test_line_count = 2 packs-after && + cat packs-after | grep "pack/test-1-" && + cat packs-after | grep "pack/pack-" ' test_done -- gitgitgadget
