dovecot - Oct 2015 - Memory leak or misconfiguration: Repeated allocation of very large block

Dear all,

I am using Dovecot 2.2.19 and I keep on getting the following warnings in my
mail.log file on FreeBSD 10:

Oct 24 10:45:28 server1 dovecot: imap: Error: GC Warning: Repeated allocation of
very large block (appr. size 20480):
Oct 24 10:45:28 server1 dovecot: imap: Error: 	May lead to memory leak and poor
performance.

I am wondering whether this is a configuration issue (i.e. a mistake in my
current config) or whether I am hitting a bug. What?s the best way of figuring
this one out? I tried increasing the verbosity of the logs but it did not really
provide me with further information.

Any ideas?

Here is my config:

--

[root at server1 ~]# dovecot -n
# 2.2.19: /usr/local/etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.9 (357ac0a0e68b+)
# OS: FreeBSD 10.1-RELEASE amd64  zfs
auth_cache_size = 50 M
auth_mechanisms = plain login
default_vsz_limit = 512 M
disable_plaintext_auth = no
first_valid_uid = 1008
last_valid_uid = 1008
login_greeting = Ready.
mail_gid = 1008
mail_location = maildir:/var/mail/vdomains/%d/%n
mail_max_keyword_length = 128
mail_max_userip_connections = 20
mail_uid = 1008
maildir_stat_dirs = yes
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
passdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf
  driver = sql
}
passdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf
  driver = sql
}
plugin {
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
}
postmaster_address = sebastian at wolfgarten.com
protocols = imap pop3 lmtp sieve
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = vmail
    mode = 0666
    user = vmail
  }
  user = $default_internal_user
}
service imap-login {
  inet_listener imap {
    port = 143
  }
  inet_listener imaps {
    port = 993
    ssl = yes
  }
  process_min_avail = 3
  service_count = 0
  vsz_limit = 512 M
}
service imap-postlogin {
  executable = script-login /usr/local/etc/popafter.sh
  user = $default_internal_user
}
service imap {
  executable = imap imap-postlogin
  process_limit = 1024
  vsz_limit = 512 M
}
service lmtp {
  unix_listener lmtp {
    mode = 0666
  }
}
service managesieve-login {
  inet_listener sieve {
    port = 4190
  }
}
service pop3-login {
  inet_listener pop3 {
    port = 110
  }
  inet_listener pop3s {
    port = 995
    ssl = yes
  }
}
service pop3-postlogin {
  executable = script-login /usr/local/etc/popafter.sh
  user = $default_internal_user
}
service pop3 {
  executable = pop3 pop3-postlogin
  process_limit = 1024
}
ssl_ca = </etc/postfix/ca.pem
ssl_cert = </etc/postfix/server1.wolfgarten.com.crt.chain
ssl_cipher_list =
ALL:!LOW:!ADH:!SSLv2:SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS:!RC4:+HIGH:+MEDIUM
ssl_key = </etc/postfix/server1.wolfgarten.com.key
ssl_protocols = !SSLv2 !SSLv3
userdb {
  driver = prefetch
}
userdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf
  driver = sql
}
userdb {
  driver = prefetch
}
userdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf
  driver = sql
}
protocol lda {
  mail_plugins = " sieve"
}

--

Many thanks.

Best regards
Sebastian
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On 24 Oct 2015, at 14:59, Sebastian Wolfgarten <sebastian at
wolfgarten.com> wrote:
> 
> Dear all,
> 
> I am using Dovecot 2.2.19 and I keep on getting the following warnings in
my mail.log file on FreeBSD 10:
> 
> Oct 24 10:45:28 server1 dovecot: imap: Error: GC Warning: Repeated
allocation of very large block (appr. size 20480):
> Oct 24 10:45:28 server1 dovecot: imap: Error: 	May lead to memory leak and
poor performance.
> 
> I am wondering whether this is a configuration issue (i.e. a mistake in my
current config) or whether I am hitting a bug. What?s the best way of figuring
this one out? I tried increasing the verbosity of the logs but it did not really
provide me with further information.
I guess you have configured Dovecot --with-gc? I guess it's possible this is
a bug, but it could just as well be a false alarm. In general I don't
recommend/support --with-gc option (and I should probably just remove it
altogether). The easiest and the most usable way of finding memory leaks is to
run with valgrind (which must be done without-gc):

service imap {
  executable = /usr/bin/valgrind -q --show-reachable=yes --leak-check=full
/usr/libexec/dovecot/imap
}

I'm not aware of any memory leaks right now.

Hi Timo,

alright, thanks I will recompile without gc - this is a standard build option on
FreeBSD but I will get the port maintainer to maybe change this.

Best regards
Sebastian
> Am 24.10.2015 um 23:19 schrieb Timo Sirainen <tss at iki.fi>:
> 
> On 24 Oct 2015, at 14:59, Sebastian Wolfgarten <sebastian at
wolfgarten.com> wrote:
>> 
>> Dear all,
>> 
>> I am using Dovecot 2.2.19 and I keep on getting the following warnings
in my mail.log file on FreeBSD 10:
>> 
>> Oct 24 10:45:28 server1 dovecot: imap: Error: GC Warning: Repeated
allocation of very large block (appr. size 20480):
>> Oct 24 10:45:28 server1 dovecot: imap: Error: 	May lead to memory leak
and poor performance.
>> 
>> I am wondering whether this is a configuration issue (i.e. a mistake in
my current config) or whether I am hitting a bug. What?s the best way of
figuring this one out? I tried increasing the verbosity of the logs but it did
not really provide me with further information.
> 
> I guess you have configured Dovecot --with-gc? I guess it's possible
this is a bug, but it could just as well be a false alarm. In general I
don't recommend/support --with-gc option (and I should probably just remove
it altogether). The easiest and the most usable way of finding memory leaks is
to run with valgrind (which must be done without-gc):
> 
> service imap {
>  executable = /usr/bin/valgrind -q --show-reachable=yes --leak-check=full
/usr/libexec/dovecot/imap
> }
> 
> I'm not aware of any memory leaks right now.
> 
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