An I/O error occured while sending to the backend.

Hi,

I am running PostgreSQL version 8.3 with this conf[1].
The Operating System is a GNU/Linux x86_64 Kernel 2.6.28-11-server,
Distribution: Ubuntu SMP.
Some sysctl I think it's important to relate[2]
Memory and Proc information [3].
The log error is [4].
Aditional information:
I am getting this error using glassfish and postgresql: " Caused by:
org.postgresql.util.PSQLException: An I/O error occured while sending to the
backend."
Both glassfish and pgsql are localhost. The connection is made using JPA
(using localhost to connect)[5].
There's no firewall filtering or blocking it.
I have other environment but CentOS using the same version of pgsql and
glassfish with no errors.
What can it be? No errors in pgsql logs.

[1] - postgresql.conf
data_directory = '/var/lib/postgresql/8.3/main'
hba_file = '/etc/postgresql/8.3/main/pg_hba.conf'
ident_file = '/etc/postgresql/8.3/main/pg_ident.conf'
external_pid_file = '/var/run/postgresql/8.3-main.pid'

port = 5432
max_connections = 500
shared_buffers = 32MB
max_fsm_pages = 204800

log_min_messages = error
log_min_error_statement = error
debug_print_parse = off
debug_print_rewritten = off
debug_print_plan = off
debug_pretty_print = off
log_connections = on
log_disconnections = on
log_line_prefix = '%t '
log_statement = 'all'
datestyle = 'iso, mdy'
lc_messages = 'en_US.UTF-8'
lc_monetary = 'en_US.UTF-8'
lc_numeric = 'en_US.UTF-8'
lc_time = 'en_US.UTF-8'
default_text_search_config = 'pg_catalog.english'

[2] sysctl

vm.overcommit_memory = 0
vm.panic_on_oom = 0
vm.oom_kill_allocating_task = 0
vm.oom_dump_tasks = 0
vm.overcommit_ratio = 50
vm.page-cluster = 3
vm.dirty_background_ratio = 40
vm.dirty_ratio = 40
vm.dirty_writeback_centisecs = 500
vm.dirty_expire_centisecs = 3000
vm.nr_pdflush_threads = 2
vm.swappiness = 60
vm.nr_hugepages = 0
vm.hugetlb_shm_group = 0
vm.hugepages_treat_as_movable = 0
vm.nr_overcommit_hugepages = 0
vm.lowmem_reserve_ratio = 256 256 32
vm.drop_caches = 0
vm.min_free_kbytes = 9939
vm.percpu_pagelist_fraction = 0
vm.max_map_count = 65536
vm.laptop_mode = 0
vm.block_dump = 0
vm.vfs_cache_pressure = 100
vm.legacy_va_layout = 0
vm.stat_interval = 1
vm.mmap_min_addr = 65536
kernel.shmmax = 68719476736
kernel.shmmni = 4096

[3] - Proc / Mem Info
Proc 16 cores:
model name : Intel(R) Xeon(R) CPU E5520 @ 2.27GHz
cpu MHz : 2260.929
cache size : 8192 KB
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx
rdtscp l
m constant_tsc arch_perfmon pebs bts rep_good xtopology pni dtes64 monitor
ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 lahf_lm ida
tpr_shadow v
nmi flexpriority ept vpid
bogomips : 4521.85
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual

Mem:
total used free shared buffers cached
Mem: 6023960 4969208 1054752 0 156176 3833340
-/+ buffers/cache: 979692 5044268
Swap: 3903784 47752 3856032

[4] Log error:
http://pastebin.com/qjUbaFmM

[5] Connection:
<property name="toplink.jdbc.driver" value="org.postgresql.Driver" />
<property name="toplink.jdbc.url"
value="jdbc:postgresql://localhost:5432/hidden" />
<property name="toplink.jdbc.user" value="tcpmexico" />
<property name="toplink.jdbc.password" value="MY_PASSWD" />

Any ideas will be welcome!

Let me know if I need to post more information or if this is not the
adequated place for the post.

Thanks

-B