As a supplement to the above:

Kamailio is launched with -m 64 -M 4.

After researching, I've doubled the values and we'll see shortly.

kamctl stats shmem
{
"jsonrpc": "2.0",
"result": [
"shmem:fragments = 11935",
"shmem:free_size = 36995032",
"shmem:max_used_size = 66744520",
"shmem:real_used_size = 30113832",
"shmem:total_size = 67108864",
"shmem:used_size = 20683936"
],
"id": 30547
}

kamcmd pkg.stats returns
{
entry: 0
pid: 14908
rank: 0
used: 1684296
free: 1567448
real_used: 2626856
total_size: 4194304
total_frags: 1974
}
{
entry: 1
pid: 14909
rank: 1
used: 1776064
free: 1285152
real_used: 2909152
total_size: 4194304
total_frags: 2283
}
{
entry: 2
pid: 14910
rank: 2
used: 1776608
free: 1397344
real_used: 2796960
total_size: 4194304
total_frags: 1200
}
{
entry: 3
pid: 14911
rank: 3
used: 1776504
free: 1398488
real_used: 2795816
total_size: 4194304
total_frags: 1190
}
{
entry: 4
pid: 14912
rank: 4
used: 1776616
free: 1397440
real_used: 2796864
total_size: 4194304
total_frags: 1199
}
{
entry: 5
pid: 14913
rank: 5
used: 1776696
free: 1395072
real_used: 2799232
total_size: 4194304
total_frags: 1226
}
{
entry: 6
pid: 14914
rank: 6
used: 1776808
free: 1399120
real_used: 2795184
total_size: 4194304
total_frags: 1186
}
{
entry: 7
pid: 14915
rank: 7
used: 1776800
free: 1399544
real_used: 2794760
total_size: 4194304
total_frags: 1182
}
{
entry: 8
pid: 14916
rank: 8
used: 1776808
free: 1399536
real_used: 2794768
total_size: 4194304
total_frags: 1182
}
{
entry: 9
pid: 14917
rank: -1
used: 1775848
free: 1416200
real_used: 2778104
total_size: 4194304
total_frags: 1045
}
{
entry: 10
pid: 14918
rank: -1
used: 1775848
free: 1416200
real_used: 2778104
total_size: 4194304
total_frags: 1045
}
{
entry: 11
pid: 14919
rank: -1
used: 1775848
free: 1416928
real_used: 2777376
total_size: 4194304
total_frags: 1038
}
{
entry: 12
pid: 14920
rank: -2
used: 1775848
free: 1416928
real_used: 2777376
total_size: 4194304
total_frags: 1038
}
{
entry: 13
pid: 14921
rank: -2
used: 1841304
free: 1351368
real_used: 2842936
total_size: 4194304
total_frags: 1038
}
{
entry: 14
pid: 14922
rank: -2
used: 1786392
free: 1405864
real_used: 2788440
total_size: 4194304
total_frags: 1032
}
{
entry: 15
pid: 14923
rank: -1
used: 1778072
free: 1414392
real_used: 2779912
total_size: 4194304
total_frags: 1032
}
{
entry: 16
pid: 14924
rank: -1
used: 1778072
free: 1414392
real_used: 2779912
total_size: 4194304
total_frags: 1032
}
{
entry: 17
pid: 14925
rank: -1
used: 1778072
free: 1414392
real_used: 2779912
total_size: 4194304
total_frags: 1032
}
{
entry: 18
pid: 14926
rank: -1
used: 1778464
free: 1413896
real_used: 2780408
total_size: 4194304
total_frags: 1031
}
{
entry: 19
pid: 14927
rank: -1
used: 1778072
free: 1414392
real_used: 2779912
total_size: 4194304
total_frags: 1032
}
{
entry: 20
pid: 14928
rank: 9
used: 1858696
free: 1331272
real_used: 2863032
total_size: 4194304
total_frags: 1035
}
{
entry: 21
pid: 14929
rank: 10
used: 1858552
free: 1331520
real_used: 2862784
total_size: 4194304
total_frags: 1034
}
{
entry: 22
pid: 14930
rank: 11
used: 1858672
free: 1331504
real_used: 2862800
total_size: 4194304
total_frags: 1033
}
{
entry: 23
pid: 14933
rank: 12
used: 1858552
free: 1331416
real_used: 2862888
total_size: 4194304
total_frags: 1035
}
{
entry: 24
pid: 14934
rank: -4
used: 1765848
free: 1485584
real_used: 2708720
total_size: 4194304
total_frags: 1974
}

---------- Forwarded message ---------
From: Tom D <dworakowski.tom@gmail.com>
Date: Mon, Nov 18, 2019 at 7:59 PM
Subject: Websocket immediately disconnecting
To: <sr-users@lists.kamailio.org>

Hi David,

Thanks for your reply.

After increasing the verbosity of the debugging, I found the following entries. So am I understanding the log correctly: the websocket module is trying to get some free memory (from Kamilio's general pool?). It doesn't receive any yet proceeds with parsing the response (I get this same parsing error even when it's working) and ultimately, it doesn't register the websocket?

I appreciate your (or anyone's) thoughts.

Regards, Tom

Nov 19 02:44:44 MY-HOSTNAME /usr/sbin/kamailio[14928]: CRITICAL: tls [tls_domain.c:737]: sr_ssl_ctx_info_callback(): SSL handshake started
Nov 19 02:44:44 MY-HOSTNAME /usr/sbin/kamailio[14928]: CRITICAL: tls [tls_domain.c:749]: sr_ssl_ctx_info_callback(): SSL handshake done
Nov 19 02:44:44 MY-HOSTNAME /usr/sbin/kamailio[14928]: CRITICAL: tls [tls_domain.c:753]: sr_ssl_ctx_info_callback(): SSL disable renegotiation
Nov 19 02:44:44 MY-HOSTNAME /usr/sbin/kamailio[14928]: CRITICAL: tls [tls_server.c:431]: tls_accept(): tls_accept: new connection from HI.DD.E.N:63356 using TLSv1/SSLv3 AES256-GCM-SHA384 256
Nov 19 02:44:44 MY-HOSTNAME /usr/sbin/kamailio[14928]: CRITICAL: tls [tls_server.c:434]: tls_accept(): tls_accept: local socket: HI.DD.E.N:8089
Nov 19 02:44:44 MY-HOSTNAME /usr/sbin/kamailio[14928]: CRITICAL: tls [tls_server.c:445]: tls_accept(): tls_accept: client did not present a certificate
Nov 19 02:44:45 MY-HOSTNAME /usr/sbin/kamailio[14928]: CRITICAL: <script>: 857:HTTP Request Received
Nov 19 02:44:45 MY-HOSTNAME /usr/sbin/kamailio[14928]: ERROR: <core> [core/mem/q_malloc.c:291]: qm_find_free(): qm_find_free(0x7f8b8cdcd000, 65728); Free fragment not found!
Nov 19 02:44:45 MY-HOSTNAME /usr/sbin/kamailio[14928]: ERROR: <core> [core/mem/q_malloc.c:425]: qm_malloc(): qm_malloc(0x7f8b8cdcd000, 65728) called from websocket: ws_conn.c: wsconn_add(197), module: websocket; Free fragment not found!
Nov 19 02:44:45 MY-HOSTNAME /usr/sbin/kamailio[14928]: ERROR: websocket [ws_conn.c:199]: wsconn_add(): allocating shared memory
Nov 19 02:44:45 MY-HOSTNAME /usr/sbin/kamailio[14928]: ERROR: <core> [core/parser/parse_fline.c:262]: parse_first_line(): parse_first_line: bad message (offset: 22)
Nov 19 02:44:45 MY-HOSTNAME /usr/sbin/kamailio[14928]: ERROR: <core> [core/parser/msg_parser.c:681]: parse_msg(): ERROR: parse_msg: message=<HTTP/1.1 101 Switching Protocols#015#012Sia: SIP/2.0/TLS HI.DD.E.N:63356#015#012Access-Control-Allow-Origin: https://www.doubango.org#015#012Sec-WebSocket-Protocol: sip#015#012Upgrade: websocket#015#012Connection: upgrade#015#012Sec-WebSocket-Accept: taS0s3Z7t4tOhklSbJDLGmSSYsY=#015#012Server: kamailio (5.2.5 (x86_64/linux))#015#012Content-Length: 0#015#012#015#012>
Nov 19 02:44:45 MY-HOSTNAME /usr/sbin/kamailio[14928]: ERROR: websocket [ws_frame.c:583]: ws_frame_receive(): WebSocket connection not found