Hello,

We run a 5 instances dovecot cluster ondebian 11 virtual machines, a dovecot proxy, 2directors and 2dovecot backends. All dovecot instances run version 2.3.20. We use a glusterfs mounted volume on the backends forthe mail storage.  Our users all use thunderbird mail client and they do not report any issue with the imap service. Since we have configured the dovecot cluster we see multiple random imap crashes with signal 11 and timeout leaks in the logs on both the backends for multiple users.

Is this is a configuration problem or a bug with imapc or imap;  I would appreciate if you could assist us to debug this further.

A coredump is attached if it helps.

The logs look similar to this:

Jun 01 16:21:13 doveb0-rmt0-cn1 dovecot[75106]: imap(user@domie02.com)<105800><BxSqJw39DLgKZQD+>: Warning: Timeout leak: 0x7f9a92c0c1c0 (imapc-client.c:475) Jun 01 16:21:13 doveb0-rmt0-cn1 dovecot[75106]: imap(user@domie02.com)<105800><BxSqJw39DLgKZQD+>: Warning: Raw backtrace for leaks: /usr/lib/dovecot/libdovecot.so.0(backtrace_append+0x42) [0x7f9a92a7e872] -> /usr/lib/dovecot/libdovecot.so.0(backtrace_get+0x1e) [0x7f9a92a7e98e] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_destroy+0x2b5) [0x7f9a92aa21e5] -> /usr/lib/dovecot/libdovecot-storage.so.0(imapc_client_run+0x115) [0x7f9a92c0bcb5] -> /usr/lib/dovecot/libdovecot-storage.so.0(imapc_mailbox_run_nofetch+0x20) [0x7f9a92c089f0] -> /usr/lib/dovecot/libdovecot-storage.so.0(imapc_mailbox_sync_init+0x868) [0x7f9a92c0b198] -> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_sync_init+0x58) [0x7f9a92bbfa68] -> dovecot/imap(imap_sync_init+0x95) [0x5605e4ebbe55] -> dovecot/imap(+0x17343) [0x5605e4ea5343] -> dovecot/imap(cmd_idle+0xb4) [0x5605e4ea5674] -> dovecot/imap(command_exec+0xa4) [0x5605e4eb04d4] -> dovecot/imap(+0x2044f) [0x5605e4eae44f] -> dovecot/imap(+0x204fa) [0x5605e4eae4fa] -> dovecot/imap(client_handle_input+0x1b5) [0x5605e4eae9d5] -> dovecot/imap(client_input+0x70) [0x5605e4eaef40] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x69) [0x7f9a92aa1819] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0x132) [0x7f9a92aa2f02] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0x50) [0x7f9a92aa18c0] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x40) [0x7f9a92aa1a80] -> /usr/lib/dovecot/libdovecot.so.0(master_service_run+0x13) [0x7f9a92a143c3] -> dovecot/imap(main+0x4fa) [0x5605e4e9ff0a] -> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xea) [0x7f9a927d2d0a] -> dovecot/imap(_start+0x2a) [0x5605e4e9ffca] Jun 01 16:23:49 doveb0-rmt0-cn1 dovecot[75106]: imap(user@domie02.com)<105800><BxSqJw39DLgKZQD+>: Fatal: master: service(imap): child 105800 killed with signal 11 (core dumped)

Below i post the dovecot configuration of one of the two dovecot backends:

# 2.3.20 (80a5ac675d): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.20 (149edcf2) # OS: Linux 5.10.0-23-amd64 x86_64 Debian 11.7 fuse.glusterfs # Hostname: doveb0-rmt0-cn1 auth_cache_negative_ttl = 5 mins auth_cache_size = 50 M auth_default_realm = domie02.com auth_master_user_separator = * auth_mechanisms = plain login auth_verbose = yes auth_worker_max_count = 16 disable_plaintext_auth = no first_valid_uid = 499 hostname = smtp.domie02.com imapc_features = fetch-bodystructure fetch-headers rfc822.size search modseq acl delay-login imapc_host = 10.101.0.250 imapc_max_idle_time = 5 mins imapc_password = # hidden, use -P to show it imapc_sasl_mechanisms = plain login imapc_ssl = starttls imapc_ssl_verify = no last_valid_uid = 499 lda_mailbox_autocreate = yes lda_mailbox_autosubscribe = yes login_greeting = You have successfully logged in to domie02.com IMAP server login_trusted_networks = 10.101.0.74 10.101.0.73 mail_always_cache_fields = flags hdr.* date.received date.sent mail_cache_fields = flags date.received guid size.physical size.virtual imap.bodystructure body.snippet mail_debug = yes mail_fsync = always mail_location = mdbox:/var/vmail/%d/%n/mdbox:VOLATILEDIR=/dev/shm/dovecot/%2.256Nu/%d/%n mail_plugins = " notify mail_log zlib acl" mail_privileged_group = mail managesieve_notify_capability = mailto managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext mdbox_rotate_size = 200 M mmap_disable = yes namespace Domie02 { list = children location = imapc:/var/vmail/%d/%n/shared/indexes/%%n:INDEXPVT=/var/vmail/%d/%n/shared-pvt/%%n:VOLATILEDIR=/dev/shm/dovecot/%2.256Nu/%d/%n/%%n prefix = shared.%%n. separator = . subscriptions = no type = shared } namespace inbox { inbox = yes location = mailbox Drafts { special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Spam.Virus { auto = subscribe } mailbox Spam { auto = subscribe } mailbox Trash { special_use = \Trash } prefix = separator = . subscriptions = yes type = private } passdb { args = password=#hidden_use-P_to_show# driver = static master = yes override_fields = allow_real_nets=127.0.0.0/8,local,10.101.0.74,10.101.0.73 userdb_acl_user=%{auth_user} userdb_namespace/Domie02/disabled=yes result_success = continue } passdb { args = password=#hidden_use-P_to_show# driver = static override_fields = allow_real_nets=127.0.0.0/8,local,10.101.0.74,10.101.0.73 result_success = continue } passdb { args = /etc/dovecot/dovecot-ldap-users.conf.ext driver = ldap } passdb { args = /etc/dovecot/dovecot-ldap-groups.conf.ext driver = ldap } plugin { acl = vfile:/etc/dovecot/global-acls/%d/master-dovecot-acl:cache_secs=300 acl_defaults_from_inbox = yes acl_globals_only = no acl_shared_dict =file:/var/dovecot-acl/%d/shared-mailboxes.db imap_compress_deflate_level = 6 mail_log_events = flag_change mail_log_fields = uid box flags sieve =file:~/sieve;active=~/sieve/%n.sieve sieve_before = /var/vmail/global-sieve/global.sieve sieve_env_email_address = %u sieve_env_mailbox_prefix = %{userdb:mailbox_prefix} sieve_global = /var/vmail/sieve sieve_global_extensions = +editheader +vnd.dovecot.environment zlib_save = zstd zlib_save_level = 5 } protocols = " imap lmtp sieve submission" service auth-worker { user = dovecot } service auth { unix_listener auth-userdb { group = mail mode = 0666 user = vmail } } service doveadm { inet_listener dovadm-dom-mgmt { address = 10.100.1.71 port = 8080 ssl = no } inet_listener dovadm-dom { address = 10.101.0.71 port = 8080 ssl = no } vsz_limit = 256 M } service imap-login { inet_listener imap-dom { address = 10.101.0.71 port = 143 ssl = no } inet_listener imap { port = 0 } inet_listener imaps-dom { address = 10.101.0.71 port = 993 ssl = yes } inet_listener imaps { port = 0 } process_limit = 400 process_min_avail = 2 service_count = 20 vsz_limit = 512 M } service imap { process_limit = 2048 process_min_avail = 0 service_count = 1 vsz_limit = 4 G } service lmtp { inet_listener lmtp-dom { address = 10.101.0.71 port = 24 ssl = no } process_limit = 0 process_min_avail = 0 service_count = 0 unix_listener lmtp { mode = 0666 } vsz_limit = 256 M } service managesieve-login { inet_listener sieve-dom { address = 10.101.0.71 port = 4190 ssl = no } inet_listener sieve { port = 0 } process_limit = 0 process_min_avail = 0 service_count = 0 vsz_limit = 64 M } service managesieve { process_limit = 1024 process_min_avail = 0 service_count = 1 vsz_limit = 256 M } service submission-login { inet_listener submission-dom { address = 10.101.0.71 port = 587 ssl = no } inet_listener submission { port = 0 } inet_listener submissions-dom { address = 10.101.0.71 port = 465 ssl = yes } process_limit = 250 process_min_avail = 2 service_count = 1 vsz_limit = 256 M } service submission { process_limit = 1024 process_min_avail = 0 service_count = 1 vsz_limit = 256 M } ssl = required ssl_cert = </etc/ssl/certs/doveb0-rmt0-cn1.mail.rmt.domie02.com.pem ssl_client_ca_dir = /etc/ssl/certs ssl_key = # hidden, use -P to show it submission_max_mail_size = 30000 k submission_relay_host = 10.101.0.7 submission_relay_port = 587 submission_relay_ssl = starttls submission_relay_ssl_verify = no submission_relay_trusted = yes userdb { driver = prefetch } userdb { args = /etc/dovecot/dovecot-ldap-users.conf.ext driver = ldap } userdb { args = /etc/dovecot/dovecot-ldap-groups.conf.ext driver = ldap } protocol lmtp { mail_plugins = " notify mail_log zlib acl sieve acl" } protocol lda { mail_plugins = " notify mail_log zlib acl sieve acl" } protocol imap { mail_max_userip_connections = 100 mail_plugins = " notify mail_log zlib acl" } protocol sieve { mail_max_userip_connections = 40 } protocol submission { mail_max_userip_connections = 70 } local 10.101.0.71 { doveadm_allowed_commands = doveadm_password = # hidden, use -P to show it } local 10.100.1.71 { doveadm_allowed_commands = doveadm_password = # hidden, use -P to show it }

} Thank you, Nikolaos Pyrgiotis