ewe@9 benchmarks

ewe@9 benchmarks against ewe@8 and nine other BEAM web servers over HTTP/1.1 and cleartext HTTP/2, measured on September 29 2026. The scripts and the exact method are in the repository’s benchmark directory.

Setup

machine     AMD Ryzen 7 5700G, 12 vCPUs in a KVM virtual machine, Linux 7.2
toolchain   Gleam 1.18.0, Erlang/OTP 29, Elixir 1.19.4
cpu         server pinned to CPUs 0-5, load generator to CPUs 6-11
throughput  h2load (nghttp2 1.70.0), 4 threads, 50 connections,
            10 streams per connection on HTTP/2,
            3 runs of 10s after a 3s warmup, median reported
latency     zrk 2.5.0, 4 threads, 50 connections,
            10 streams per connection on HTTP/2,
            10s per rate after a 3s warmup

Servers

server	version	HTTP/1.1	HTTP/2
`ewe@9`	9.0.0	yes	yes
`ewe@8`	8.0.0	yes	yes
`mist`	6.0.3	yes	no
`elli`	3.3.0	yes	no
`bandit`	1.12.0	yes	yes
`httpd`	inets 9.7.1 (OTP 29)	yes	no
`roadrunner`	0.8.0	yes	yes
`chatterbox`	0.8.0	no	yes
`cowboy`	2.19.0	yes	yes
`mochiweb`	3.5.0	yes	no
`yaws`	2.3.1	yes	no

Every server runs a production build with the default settings except:

cowboy’s max_keepalive and max_received_frame_rate are lifted.
elli, httpd, mochiweb and yaws have Nagle’s algorithm disabled.
yaws has its access and auth logs disabled and serves files without sendfile.

bandit, chatterbox, elli, httpd and mochiweb have no native SSE API; elli and httpd cannot read a request body incrementally.

Cases

case	request	response
`hello`	`GET /hello`	`Hello, Joe!`
`hello_headers`	`GET /hello` with 7 extra headers	`Hello, Joe!`
`echo_1kb`	`POST /echo`, 1KiB body	the body
`echo_1kb_headers`	`POST /echo`, 1KiB body, 7 extra headers	the body
`echo_10kb`	`POST /echo`, 10KiB body	the body
`echo_chunked_10kb`	`POST /echo/chunked`, 10KiB body	the body, read incrementally
`file_tiny`	`GET /file/tiny`	1KiB file
`file_small`	`GET /file/small`	100KiB file
`file_big`	`GET /file/big`	5MiB file
`stream`	`GET /stream`	2 chunks, `hello,` and `Joe!`
`stream_small`	`GET /stream/small`	100 x 64B chunks
`stream_big`	`GET /stream/big`	64 x 16KiB chunks
`sse`	`GET /sse`	32 events
`sse_small`	`GET /sse/small`	100 events
`sse_big`	`GET /sse/big`	64 x 16KiB events

Throughput

Requests per second, higher is better. Rps above 200_000 are limited by the load generator so small differences in numbers between servers may be not accurate.

HTTP/1.1

case	ewe@9	ewe@8	mist	elli	bandit	httpd	roadrunner	cowboy	mochiweb	yaws
hello	266,046	283,205	199,559	276,538 ~	152,776	103,490	246,009	116,951	180,532	165,957
hello_headers	223,539	221,090	159,693	219,366	124,005	87,236	197,914	95,855	133,774	118,936
echo_1kb	230,146	241,469	173,837	242,937	139,177	76,045	213,377	82,815	158,673	143,420
echo_1kb_headers	201,422	198,650	143,568	205,644	116,815	57,985	185,188	72,432	122,660	105,882
echo_10kb	188,255	190,263	158,321	166,777	119,510	12,513	183,832	66,638	116,616	111,922
echo_chunked_10kb	188,239	191,041	155,390	-	109,274	-	183,607	63,295	117,395	113,277
file_tiny	69,500	69,346	37,838	39,857	49,345	34,046	38,771	33,116	64,847 ~	84,558 ~
file_small	58,114	59,962	35,100	37,018	44,618	29,559	35,878	30,641	20,220	13,480
file_big	3,695	3,622	3,599	3,657	3,610	1,303 ~	3,586	3,648	556	575 ~
stream	142,687	144,423	stalled	stalled	85,869	102,903	35,489 ~	79,342	100,729	101,332
stream_small	8,165	8,092 ~	stalled	stalled	7,147	8,466 ~	6,759	6,787	7,340	6,219
stream_big	8,359	8,420 ~	stalled	stalled	7,131	8,440	7,700	7,051	7,445	6,504
sse	17,705	18,178	stalled	-	-	-	13,090	13,747	-	16,945
sse_small	6,344	6,484	stalled	-	-	-	6,270	5,017	-	5,900
sse_big	6,488	6,370	stalled	-	-	-	2,465	2,361	-	6,131

HTTP/2

case	ewe@9	ewe@8	bandit	roadrunner	chatterbox	cowboy
hello	360,596	160,289	81,403	211,119	8,267	134,163
hello_headers	259,677	136,404	73,186	172,403	8,255	77,239
echo_1kb	199,023	118,402	68,576	183,023	7,310	90,615
echo_1kb_headers	162,428	107,699	62,943	152,565	7,227	60,352
echo_10kb	132,853	96,793	57,692	138,248	8,476	76,147
echo_chunked_10kb	132,779	92,030	54,870	135,459	8,487	69,822
file_tiny	128,795	81,594	39,196	34,993	8,385	30,792
file_small	45,262 ~	47,144 ~	30,113 ~	25,000	26,683	11,224
file_big	982 ~	507 ~	750	1,066 ~	721 ~	321
stream	203,349	87,498	52,199	126,173	8,734	88,728
stream_small	13,156	4,831	4,500	6,424	10,922	5,884
stream_big	11,957 ~	5,233	4,842	6,678	stalled	6,212
sse	24,448	9,825	-	15,974	-	12,448
sse_small	8,667	3,415	-	5,673	-	4,298
sse_big	5,449	3,208	-	2,193	-	2,134

Latency

p99 latency at a fixed offered rate with no coordinated omission, lower is better. Every server gets the same rates.

HTTP/1.1

case	req/s	ewe@9	ewe@8	mist	elli	bandit	httpd	roadrunner	cowboy	mochiweb	yaws
hello	50,000	169us	162us	1.71ms	132us	236us	490us	153us	429us	148us	159us
hello	100,000	1.35ms	1.26ms	2.79ms	833us	3.04ms	37.78ms	1.18ms	14.32ms	2.49ms	2.82ms
hello	150,000	3.19ms	3.21ms	3.32ms	2.90ms	355.71ms	overloaded	3.15ms	overloaded	6.25ms	9.35ms
hello_headers	50,000	218us	207us	231us	171us	318us	2.70ms	198us	910us	422us	437us
hello_headers	100,000	1.26ms	2.17ms	3.10ms	2.12ms	3.33ms	overloaded	2.05ms	overloaded	16.10ms	6.70ms
hello_headers	150,000	3.35ms	3.67ms	418.43ms	2.88ms	overloaded	overloaded	4.28ms	overloaded	overloaded	overloaded
echo_1kb	50,000	162us	159us	195us	162us	208us	3.96ms	167us	2.77ms	253us	220us
echo_1kb	100,000	1.83ms	1.68ms	2.52ms	1.23ms	2.84ms	overloaded	2.73ms	overloaded	3.93ms	3.63ms
echo_1kb	150,000	3.65ms	4.57ms	11.44ms	3.15ms	overloaded	overloaded	3.17ms	overloaded	18.38ms	243.65ms
echo_1kb_headers	40,000	156us	176us	272us	159us	295us	3.39ms	166us	1.52ms	259us	236us
echo_1kb_headers	80,000	1.66ms	832us	3.07ms	561us	3.25ms	overloaded	680us	overloaded	3.77ms	3.81ms
echo_1kb_headers	120,000	3.61ms	2.94ms	8.80ms	2.87ms	overloaded	overloaded	3.10ms	overloaded	overloaded	overloaded
echo_10kb	20,000	161us	157us	195us	154us	188us	overloaded	169us	343us	201us	199us
echo_10kb	60,000	469us	320us	317us	554us	2.51ms	overloaded	253us	32.55ms	3.24ms	2.87ms
echo_10kb	100,000	1.16ms	2.26ms	3.71ms	3.18ms	4.21ms	overloaded	2.81ms	overloaded	13.04ms	106.14ms
echo_chunked_10kb	40,000	177us	139us	220us	-	356us	-	160us	2.89ms	237us	305us
echo_chunked_10kb	70,000	380us	408us	2.31ms	-	2.95ms	-	455us	overloaded	3.33ms	3.31ms
echo_chunked_10kb	100,000	3.29ms	2.40ms	3.24ms	-	27.50ms	-	3.12ms	overloaded	6.44ms	30.41ms
file_tiny	20,000	707us	398us	929us	442us	1.76ms	669us	529us	976us	1.59ms	222us
file_tiny	40,000	3.94ms	3.76ms	overloaded	181.95ms	6.53ms	overloaded	overloaded	overloaded	4.94ms	386us
file_tiny	60,000	37.87ms	54.42ms	overloaded	overloaded	overloaded	overloaded	overloaded	overloaded	160.19ms	overloaded
file_small	15,000	398us	343us	577us	508us	777us	1.10ms	571us	1.25ms	29.99ms	overloaded
file_small	30,000	3.35ms	3.01ms	4.09ms	3.76ms	3.91ms	overloaded	5.10ms	overloaded	overloaded	overloaded
file_small	45,000	9.35ms	9.60ms	overloaded	overloaded	overloaded	overloaded	overloaded	overloaded	overloaded	overloaded
file_big	500	2.07ms	1.90ms	1.92ms	1.90ms	2.38ms	2.24ms	1.86ms	2.30ms	58.06ms	25.66ms
file_big	1,000	2.40ms	2.31ms	2.45ms	2.52ms	2.36ms	4.68ms	2.52ms	2.25ms	overloaded	overloaded
file_big	1,500	2.55ms	2.50ms	2.65ms	2.58ms	2.45ms	7.49ms	2.65ms	2.44ms	overloaded	overloaded
stream	20,000	208us	199us	errors	errors	287us	256us	715us	290us	232us	253us
stream	40,000	243us	274us	errors	errors	888us	439us	overloaded	1.40ms	402us	556us
stream	60,000	668us	838us	errors	errors	3.56ms	3.12ms	overloaded	5.58ms	3.23ms	3.51ms
stream_small	3,000	1.77ms	1.72ms	errors	errors	2.15ms	1.67ms	2.13ms	2.16ms	2.08ms	2.52ms
stream_small	5,000	2.65ms	2.70ms	errors	errors	5.98ms	2.38ms	4.76ms	6.42ms	5.37ms	17.22ms
stream_small	7,000	16.05ms	11.56ms	errors	errors	overloaded	10.38ms	overloaded	overloaded	overloaded	overloaded
stream_big	3,000	1.77ms	1.76ms	errors	errors	2.06ms	1.72ms	1.92ms	1.92ms	1.97ms	2.21ms
stream_big	5,000	2.39ms	2.29ms	errors	errors	3.62ms	2.19ms	3.03ms	4.48ms	3.55ms	9.61ms
stream_big	7,000	12.43ms	15.05ms	errors	errors	452.22ms	19.45ms	61.58ms	264.06ms	103.01ms	overloaded
sse	6,000	1.03ms	1.04ms	1.77ms	-	-	-	1.28ms	1.33ms	-	1.12ms
sse	10,000	1.80ms	1.63ms	52.66ms	-	-	-	4.65ms	4.83ms	-	3.04ms
sse	14,000	5.30ms	5.65ms	overloaded	-	-	-	overloaded	366.72ms	-	16.98ms
sse_small	3,000	2.42ms	2.33ms	3.48ms	-	-	-	2.29ms	3.75ms	-	2.62ms
sse_small	5,000	7.75ms	8.28ms	overloaded	-	-	-	7.58ms	overloaded	-	33.74ms
sse_small	7,000	overloaded	overloaded	overloaded	-	-	-	overloaded	overloaded	-	overloaded
sse_big	3,000	2.25ms	2.21ms	2.57ms	-	-	-	overloaded	overloaded	-	2.35ms
sse_big	5,000	9.18ms	6.50ms	20.36ms	-	-	-	overloaded	overloaded	-	12.51ms
sse_big	7,000	overloaded	overloaded	overloaded	-	-	-	overloaded	overloaded	-	overloaded

HTTP/2

case	req/s	ewe@9	ewe@8	bandit	roadrunner	chatterbox	cowboy
hello	50,000	242us	211us	3.30ms	243us	errors	636us
hello	100,000	603us	206us	overloaded	2.88ms	errors	12.53ms
hello	150,000	4.41ms	18.79ms	overloaded	7.41ms	errors	overloaded
hello_headers	50,000	370us	257us	6.03ms	2.66ms	errors	8.24ms
hello_headers	100,000	5.93ms	26.04ms	overloaded	20.74ms	errors	overloaded
hello_headers	150,000	141.25ms	overloaded	overloaded	overloaded	errors	overloaded
echo_1kb	50,000	240us	337us	4.24ms	301us	errors	errors
echo_1kb	100,000	4.55ms	8.62ms	overloaded	3.75ms	errors	errors
echo_1kb	150,000	70.56ms	overloaded	overloaded	40.53ms	errors	errors
echo_1kb_headers	40,000	401us	354us	3.26ms	551us	errors	6.87ms
echo_1kb_headers	80,000	9.40ms	39.89ms	overloaded	6.60ms	errors	errors
echo_1kb_headers	120,000	overloaded	overloaded	overloaded	overloaded	errors	errors
echo_10kb	20,000	319us	283us	386us	211us	errors	634us
echo_10kb	60,000	343us	578us	overloaded	1.46ms	errors	errors
echo_10kb	100,000	13.96ms	overloaded	overloaded	4.99ms	errors	errors
echo_chunked_10kb	40,000	340us	343us	3.62ms	469us	errors	errors
echo_chunked_10kb	70,000	482us	677us	overloaded	2.61ms	errors	errors
echo_chunked_10kb	100,000	19.30ms	overloaded	overloaded	5.69ms	errors	errors
file_tiny	20,000	1.39ms	1.28ms	2.45ms	2.19ms	errors	1.98ms
file_tiny	40,000	4.04ms	2.55ms	overloaded	overloaded	errors	overloaded
file_tiny	60,000	8.60ms	38.86ms	overloaded	overloaded	errors	overloaded
file_small	15,000	1.40ms	921us	2.60ms	3.05ms	errors	overloaded
file_small	30,000	7.16ms	3.47ms	462.98ms	overloaded	errors	overloaded
file_small	45,000	overloaded	93.66ms	overloaded	overloaded	errors	overloaded
file_big	500	4.09ms	overloaded	3.36ms	5.64ms	errors	overloaded
file_big	1,000	58.96ms	overloaded	overloaded	15.00ms	errors	overloaded
file_big	1,500	overloaded	overloaded	overloaded	overloaded	errors	overloaded
stream	20,000	328us	341us	459us	244us	-	375us
stream	40,000	406us	360us	6.45ms	572us	-	640us
stream	60,000	1.15ms	617us	overloaded	3.29ms	-	4.95ms
stream_small	3,000	3.07ms	2.71ms	5.19ms	2.29ms	-	2.37ms
stream_small	5,000	25.61ms	203.97ms	overloaded	18.98ms	-	54.45ms
stream_small	7,000	49.14ms	overloaded	overloaded	overloaded	-	overloaded
stream_big	3,000	2.52ms	2.54ms	3.33ms	2.12ms	-	2.24ms
stream_big	5,000	16.74ms	12.80ms	260.80ms	7.68ms	-	6.16ms
stream_big	7,000	41.97ms	overloaded	overloaded	overloaded	-	overloaded
sse	6,000	2.28ms	2.58ms	-	1.25ms	-	1.78ms
sse	10,000	15.81ms	602.37ms	-	2.65ms	-	9.42ms
sse	14,000	36.40ms	overloaded	-	38.22ms	-	overloaded
sse_small	3,000	11.04ms	16.81ms	-	2.73ms	-	4.86ms
sse_small	5,000	67.42ms	overloaded	-	65.07ms	-	overloaded
sse_small	7,000	116.32ms	overloaded	-	overloaded	-	overloaded
sse_big	3,000	5.97ms	4.67ms	-	overloaded	-	overloaded
sse_big	5,000	225.09ms	overloaded	-	overloaded	-	overloaded
sse_big	7,000	overloaded	overloaded	-	overloaded	-	overloaded

chatterbox could not sustain any of the fixed rates, answering a few hundred requests per second at most. Its connections crashed whenever a client closed the socket first. Under the constant load the memory grew until the kernel killed it during the file_big case.

Legend

~ the runs for the median were more than 5% apart.
stalled none of the connections completed a second request.
overloaded the server answered less than 98% of the offered rate.
errors failed requests or non-2xx responses.
- the server does not support the case. chatterbox stopped after file_big in the latency run.