nlohmann VS JsonCpp by C++17

[zhongcy]

Hi, I test nlohmann and JsonCpp in C++17.

Env:
CentOS 7.5 64Bit
4vCPU, 8GB Mem, 100GB Disk

nlohmann Release 3.6.1
jsoncpp Release 0.10.5

[root@zhongcy home]$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/opt/rh/devtoolset-7/root/usr/libexec/gcc/x86_64-redhat-linux/7/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,lto --prefix=/opt/rh/devtoolset-7/root/usr --mandir=/opt/rh/devtoolset-7/root/usr/share/man --infodir=/opt/rh/devtoolset-7/root/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --enable-plugin --with-linker-hash-style=gnu --enable-initfini-array --with-default-libstdcxx-abi=gcc4-compatible --with-isl=/builddir/build/BUILD/gcc-7.3.1-20180303/obj-x86_64-redhat-linux/isl-install --enable-libmpx --enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 7.3.1 20180303 (Red Hat 7.3.1-5) (GCC)

Codes and result like:

`
#include "nlohmann/json.hpp"
#include <json/writer.h>

std::string sStr =
R"json(
{ "name": "myserver-consumer#consumer-1", "client_id": "myserver-consumer", "type": "consumer", "ts":1916750966985, "time":1560232284, "replyq":0, "msg_cnt":0, "msg_size":0, "msg_max":0, "msg_size_max":0, "simple_cnt":0, "metadata_cache_cnt":1, "brokers":{ "127.0.0.1:9092/1": { "name":"127.0.0.1:9092/1", "nodeid":1, "nodename":"127.0.0.1:9092", "source":"learned", "state":"INIT", "stateage":1989943, "outbuf_cnt":0, "outbuf_msg_cnt":0, "waitresp_cnt":0, "waitresp_msg_cnt":0, "tx":0, "txbytes":0, "txerrs":0, "txretries":0, "req_timeouts":0, "rx":0, "rxbytes":0, "rxerrs":0, "rxcorriderrs":0, "rxpartial":0, "zbuf_grow":0, "buf_grow":0, "wakeups":0, "connects":0, "disconnects":0, "int_latency": { "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0, "outofrange": 0, "hdrsize": 11376, "cnt":0 }, "outbuf_latency":{ "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0, "outofrange": 0, "hdrsize": 11376, "cnt":0 }, "rtt": { "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0, "outofrange": 0, "hdrsize": 13424, "cnt":0 }, "throttle": { "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0,"outofrange": 0, "hdrsize": 17520, "cnt":0 }, "req": { "Fetch": 0, "Offset": 0, "Metadata": 0, "OffsetCommit": 0, "OffsetFetch": 0, "GroupCoordinator": 0, "JoinGroup": 0, "Heartbeat": 0, "LeaveGroup": 0, "SyncGroup": 0, "SaslHandshake": 0, "ApiVersion": 0 }, "toppars":{ } } , "127.0.0.1:9092/bootstrap": { "name":"127.0.0.1:9092/bootstrap", "nodeid":-1, "nodename":"127.0.0.1:9092", "source":"configured", "state":"UP", "stateage":1993368, "outbuf_cnt":0, "outbuf_msg_cnt":0, "waitresp_cnt":0, "waitresp_msg_cnt":0, "tx":5, "txbytes":242, "txerrs":0, "txretries":0, "req_timeouts":0, "rx":5, "rxbytes":577, "rxerrs":0, "rxcorriderrs":0, "rxpartial":0, "zbuf_grow":0, "buf_grow":0, "wakeups":15, "connects":1, "disconnects":0, "int_latency": { "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0, "outofrange": 0, "hdrsize": 11376, "cnt":0 }, "outbuf_latency": { "min":32, "max":342, "avg":144, "sum":433, "stddev": 140, "p50": 59, "p75": 59, "p90": 343, "p95": 343, "p99":343, "p99_99": 343, "outofrange": 0, "hdrsize": 11376, "cnt":3 }, "rtt": { "min":3173, "max":4331, "avg":3690, "sum":11070, "stddev": 482, "p50": 3567, "p75": 3567, "p90": 4351, "p95": 4351, "p99": 4351, "p99_99": 4351, "outofrange": 0, "hdrsize": 13424, "cnt":3 }, "throttle": { "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0, "outofrange": 0, "hdrsize": 17520, "cnt":0 }, "req": { "Fetch": 0, "Offset": 0, "Metadata": 2, "OffsetCommit": 0, "OffsetFetch": 0, "GroupCoordinator": 2, "JoinGroup": 0, "Heartbeat": 0, "LeaveGroup": 0, "SyncGroup": 0, "SaslHandshake": 0, "ApiVersion": 1 }, "toppars":{ } } , "GroupCoordinator": { "name":"GroupCoordinator", "nodeid":-1, "nodename":"127.0.0.1:9092", "source":"logical", "state":"UP", "stateage":990212, "outbuf_cnt":0, "outbuf_msg_cnt":0, "waitresp_cnt":0, "waitresp_msg_cnt":0, "tx":2, "txbytes":80, "txerrs":0, "txretries":0, "req_timeouts":0, "rx":2, "rxbytes":353, "rxerrs":0, "rxcorriderrs":0, "rxpartial":0, "zbuf_grow":0, "buf_grow":0, "wakeups":6, "connects":1, "disconnects":0, "int_latency": { "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0, "outofrange": 0, "hdrsize": 11376, "cnt":0 }, "outbuf_latency": { "min":40, "max":49, "avg":44, "sum":89, "stddev": 4, "p50": 40, "p75": 49, "p90": 49, "p95": 49, "p99": 49, "p99_99": 49, "outofrange": 0, "hdrsize": 11376, "cnt":2 }, "rtt": { "min":2757, "max":2835, "avg":2796, "sum":5592, "stddev": 40, "p50": 2767, "p75": 2847, "p90": 2847, "p95": 2847, "p99": 2847, "p99_99": 2847, "outofrange": 0, "hdrsize": 13424, "cnt":2 }, "throttle": { "min":0, "max":0, "avg":0, "sum":0, "stddev": 0, "p50": 0, "p75": 0, "p90": 0, "p95": 0, "p99": 0, "p99_99": 0, "outofrange": 0, "hdrsize": 17520, "cnt":0 }, "req": { "Fetch": 0, "Offset": 0, "Metadata": 1, "OffsetCommit": 0, "OffsetFetch": 0, "GroupCoordinator": 0, "JoinGroup": 0, "Heartbeat": 0, "LeaveGroup": 0, "SyncGroup": 0, "SaslHandshake": 0, "ApiVersion": 1 }, "toppars":{ } } }, "topics":{ } , "cgrp": { "state": "up", "stateage": 987, "join_state": "init", "rebalance_age": 983, "rebalance_cnt": 2, "rebalance_reason": "group rejoin", "assignment_size": 0 }, "tx":7, "tx_bytes":322, "rx":7, "rx_bytes":930, "txmsgs":0, "txmsg_bytes":0, "rxmsgs":0, "rxmsg_bytes":0}
)json";

uint64_t timebegin = now();
if (false)
{
nlohmann::json sRoot = nlohmann::json::parse(sStr);
} else {
//JsonCpp
Json::Reader sReader;
Json::Value sRoot;
bool sRet = sReader.parse(sStr, sRoot);
}
uint64_t timeused = now() - timebegin;
LOG_DEBUG("timeused:%ld", timeused);
`

Use default: -O0

resule:
JsonCpp: timeused:513
nlohmann: timeused:5345

Why nlohmann::parse is such slower than JsonCpp::parse ?
Is nlohmann not high performance by C++17 ?
@nlohmann @theodelrieu

[zhongcy]

Ah~, jsoncpp is relase lib. jsoncpp lib use -O2/-O3, so jsoncpp lib is better than default nlohmann -O0.

[hydratim]

How was the comparison when you compiled everything with -O2?

[zhongcy]

@hydratim If we use liba.so in our code, we should compare the .so by -O2, I think.

[hydratim]

Sorry, I wasn't clear; What I meant was what did the performance of nlohmann::json look like compared to jsoncpp when you corrected your compilation difference?

[zhongcy]

@hydratim When I use -O2 to compare nlohmann::json, the performance is better.
But the nlohmann::json's performance is still lower than jsoncpp's in my test.

[hydratim]

Thanks

[laoshaw]

I just did a test myself it seems nlohmann json is actually slightly faster? I basically did the parse 10,000 loops and nolhmann takes 1092805microconds while jsoncpp takes 1368531microseconds, using c++17, use hlohmann as head file directly, while jsoncpp as a library linked in. static build give similar results(1015422microconds vs 1130625microseconds)

[nlohmann]

These benchmarks seem to reproduce this finding.