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LMDB native test harness (C)
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‎upstream-bench/README.md‎

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# Upstream LMDB Benchmark
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This directory contains the upstream C benchmark provided by the LMDB maintainer in response to [ITS#10406](https://bugs.openldap.org/show_bug.cgi?id=10406) - our report of write performance regression.
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## Purpose
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This benchmark serves as an authoritative baseline for validating LMDB performance across versions:
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- Uses native C code (eliminates JNI overhead)
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- Provided directly by LMDB maintainer
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- Matches our Java benchmark scenario (sequential append with integer keys)
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- Enables comparison between Java and C performance characteristics
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## Files
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- `mtest-append-original.c` - Upstream benchmark code from ITS#10406 (unmodified)
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- `mtest-append.c` - Modified benchmark for testing different scenarios
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- `run-upstream-bench.sh` - Test harness to run across multiple LMDB versions
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- `target/` - Build artifacts and results (gitignored)
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- `target/mtest-append` - Compiled benchmark binary
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- `target/results/` - Benchmark results for each LMDB version
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## Benchmark Characteristics
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- **Operation**: Sequential writes using `MDB_APPEND` flag
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- **Key Type**: Integer keys (`MDB_INTEGERKEY`)
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- **Entry Count**: 1,000,000
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- **Value Size**: 100 bytes (zeroed)
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- **Commit Frequency**: Every 1,000 entries (1,000 transactions total)
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- **Flags**: `MDB_NOSYNC` (for consistency with Java benchmarks)
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- **Iterations**: 3 runs per version
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## Usage
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```bash
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./run-upstream-bench.sh
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```
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Results are saved to `target/results/upstream-LMDB_<version>.txt`
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The script automatically:
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1. Checks out each LMDB version from the OpenLDAP repository
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2. Compiles the LMDB library
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3. Compiles and runs the benchmark
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4. Generates a summary comparison table
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## Performance Expectations
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Each benchmark iteration completes in ~0.075 seconds on modern hardware.
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Total runtime for all 14 versions (3 iterations each): ~1 minute.
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## Comparison with Java Benchmarks
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This C benchmark can be compared with LmdbJava benchmarks at https://lmdb-benchmark.lmdbjava.org/
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Key differences:
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- C benchmark uses raw LMDB API (no JNI overhead)
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- C benchmark commits every 1,000 entries vs Java's single-transaction approach
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- Results help isolate whether regressions are in LMDB itself or JNI layer
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## License
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Licensed under the OpenLDAP Public License (see mtest-append-original.c for copyright details).

‎upstream-bench/mtest-append-original.c‎

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/* mtest-append.c - Howard Chu's benchmark from ITS#10406 */
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/*
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* Copyright 2011-2021 Howard Chu, Symas Corp.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted only as authorized by the OpenLDAP
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* Public License.
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*
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* A copy of this license is available in the file LICENSE in the
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* top-level directory of the distribution or, alternatively, at
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* <http://www.OpenLDAP.org/license.html>.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <sys/time.h>
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#include "lmdb.h"
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#define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
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#define RES(err, expr) ((rc = expr) == (err) || (CHECK(!rc, #expr), 0))
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#define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
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"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
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int main(int argc,char * argv[])
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{
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int i = 0, j = 0, rc;
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MDB_env *env;
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MDB_dbi dbi;
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MDB_val key, data;
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MDB_txn *txn;
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int count = 1000000;
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char sval[100] = "";
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struct timeval beg, end;
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E(mdb_env_create(&env));
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E(mdb_env_set_mapsize(env, 1048576000));
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E(mdb_env_open(env, "./testdb", MDB_NOSYNC, 0664));
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E(mdb_txn_begin(env, NULL, 0, &txn));
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E(mdb_dbi_open(txn, NULL, MDB_INTEGERKEY, &dbi));
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key.mv_size = sizeof(int);
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key.mv_data = &i;
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data.mv_size = sizeof(sval);
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data.mv_data = sval;
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printf("Adding %d values\n", count);
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gettimeofday(&beg, NULL);
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for (i=0;i<count;i++) {
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E(mdb_put(txn, dbi, &key, &data, MDB_APPEND));
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j++;
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if (j == 1000) {
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E(mdb_txn_commit(txn));
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E(mdb_txn_begin(env, NULL, 0, &txn));
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j = 0;
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}
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}
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E(mdb_txn_commit(txn));
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gettimeofday(&end, NULL);
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mdb_dbi_close(env, dbi);
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mdb_env_close(env);
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end.tv_usec -= beg.tv_usec;
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if (end.tv_usec < 0) {
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end.tv_usec += 1000000;
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end.tv_sec--;
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}
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end.tv_sec -= beg.tv_sec;
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printf("Added %d values in %ld.%06ldsec\n", count, end.tv_sec, end.tv_usec);
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return 0;
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}

‎upstream-bench/mtest-append.c‎

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/* mtest-append.c - Howard Chu's benchmark from ITS#10406 */
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/*
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* Copyright 2011-2021 Howard Chu, Symas Corp.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted only as authorized by the OpenLDAP
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* Public License.
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*
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* A copy of this license is available in the file LICENSE in the
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* top-level directory of the distribution or, alternatively, at
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* <http://www.OpenLDAP.org/license.html>.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <sys/time.h>
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#include "lmdb.h"
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#define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
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#define RES(err, expr) ((rc = expr) == (err) || (CHECK(!rc, #expr), 0))
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#define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
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"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
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int main(int argc,char * argv[])
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{
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int i = 0, j = 0, rc;
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MDB_env *env;
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MDB_dbi dbi;
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MDB_val key, data;
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MDB_txn *txn;
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MDB_cursor *cursor = NULL;
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int count = 1000000;
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char sval[100] = "";
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struct timeval beg, end;
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E(mdb_env_create(&env));
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E(mdb_env_set_mapsize(env, 1048576000));
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E(mdb_env_open(env, "./testdb", MDB_NOSYNC, 0664));
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E(mdb_txn_begin(env, NULL, 0, &txn));
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E(mdb_dbi_open(txn, NULL, MDB_INTEGERKEY, &dbi));
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key.mv_size = sizeof(int);
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key.mv_data = &i;
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data.mv_size = sizeof(sval);
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data.mv_data = sval;
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printf("Adding %d values\n", count);
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gettimeofday(&beg, NULL);
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for (i=0;i<count;i++) {
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if (!cursor)
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E(mdb_cursor_open(txn, dbi, &cursor));
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E(mdb_cursor_put(cursor, &key, &data, MDB_APPEND));
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j++;
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if (j == 1000) {
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mdb_cursor_close(cursor);
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cursor = NULL;
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E(mdb_txn_commit(txn));
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E(mdb_txn_begin(env, NULL, 0, &txn));
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j = 0;
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}
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}
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if (cursor)
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mdb_cursor_close(cursor);
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E(mdb_txn_commit(txn));
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gettimeofday(&end, NULL);
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mdb_dbi_close(env, dbi);
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mdb_env_close(env);
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end.tv_usec -= beg.tv_usec;
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if (end.tv_usec < 0) {
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end.tv_usec += 1000000;
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end.tv_sec--;
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}
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end.tv_sec -= beg.tv_sec;
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printf("Added %d values in %ld.%06ldsec\n", count, end.tv_sec, end.tv_usec);
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return 0;
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}

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