BUG #2104: pg_xlog/ trace files not reclaimed by server

The following bug has been logged online:

Bug reference:      2104
Logged by:          Reuben Pasquini
Email address:      pasquini@imageworks.com
PostgreSQL version: 8.1
Operating system:   linux redhat-4.1
Description:        pg_xlog/ trace files not reclaimed by server
Details:

Hello!

It appears that when my 8.1 database is forced
to generate more than
            2*checkpoint_segments + 1
trace files under pg_xlog/, that the database
becomes confused and stops recycling the trace files.
Unfortunately - I haven't been able to catch this condition
until after it filled up the disk (hundreds of trace files)
and things crashed.  I did not have this problem running
postgres-7.4, but performance was not nearly so good as 8.1.

I'm running a high-transaction postgres-8.1 database
on a 2-proc linux box - looks like 4 procs due to hyperthreading:

Main memory size: 3931 Mbytes
4 GenuineIntel Intel(R) Xeon(TM) CPU 2.80GHz processors


Attached below is the postgresql.conf file
I was running with at the time of the last crash.
I've had a few crashes like this, but only diagnosed
the problem recently.
I increased the checkpoint-segments to 30 after the
last crash early thismorning to see if that works
around the problem.

Thanks for the help!
Reuben

---------------
# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
#   name = value
#
# (The '=' is optional.) White space may be used. Comments are introduced
# with '#' anywhere on a line. The complete list of option names and
# allowed values can be found in the PostgreSQL documentation. The
# commented-out settings shown in this file represent the default values.
#
# Please note that re-commenting a setting is NOT sufficient to revert it
# to the default value, unless you restart the postmaster.
#
# Any option can also be given as a command line switch to the
# postmaster, e.g. 'postmaster -c log_connections=on'. Some options
# can be changed at run-time with the 'SET' SQL command.
#
# This file is read on postmaster startup and when the postmaster
# receives a SIGHUP. If you edit the file on a running system, you have
# to SIGHUP the postmaster for the changes to take effect, or use
# "pg_ctl reload". Some settings, such as listen_address, require
# a postmaster shutdown and restart to take effect.


#---------------------------------------------------------------------------

# FILE LOCATIONS
#---------------------------------------------------------------------------


# The default values of these variables are driven from the -D command line
# switch or PGDATA environment variable, represented here as ConfigDir.

#data_directory = 'ConfigDir'           # use data in another directory
#hba_file = 'ConfigDir/pg_hba.conf'     # host-based authentication file
#ident_file = 'ConfigDir/pg_ident.conf  # IDENT configuration file

# If external_pid_file is not explicitly set, no extra pid file is written.
#external_pid_file = '(none)'           # write an extra pid file


#---------------------------------------------------------------------------

# CONNECTIONS AND AUTHENTICATION
#---------------------------------------------------------------------------


# - Connection Settings -

listen_addresses = '*'          # what IP address(es) to listen on;
                                        # comma-separated list of
addresses;
                                        # defaults to 'localhost', '*' =
all
#port = 5432
max_connections = 100
# note: increasing max_connections costs ~400 bytes of shared memory per
# connection slot, plus lock space (see max_locks_per_transaction).  You
# might also need to raise shared_buffers to support more connections.
#superuser_reserved_connections = 2
#unix_socket_directory = ''
#unix_socket_group = ''
#unix_socket_permissions = 0777         # octal
#bonjour_name = ''                      # defaults to the computer name

# - Security & Authentication -

#authentication_timeout = 60            # 1-600, in seconds
#ssl = off
#password_encryption = on
#db_user_namespace = off

# Kerberos
#krb_server_keyfile = ''
#krb_srvname = 'postgres'
#krb_server_hostname = ''               # empty string matches any keytab
entry
#krb_caseins_users = off

# - TCP Keepalives -
# see 'man 7 tcp' for details

#tcp_keepalives_idle = 0                # TCP_KEEPIDLE, in seconds;
                                        # 0 selects the system default
#tcp_keepalives_interval = 0            # TCP_KEEPINTVL, in seconds;
                                        # 0 selects the system default
#tcp_keepalives_count = 0               # TCP_KEEPCNT;
                                        # 0 selects the system default


#---------------------------------------------------------------------------

# RESOURCE USAGE (except WAL)
#---------------------------------------------------------------------------


# - Memory -

shared_buffers = 220000                 # min 16 or max_connections*2, 8KB
each
temp_buffers = 244000                   # min 100, 8KB each
max_prepared_transactions = 100         # can be 0 or more
# note: increasing max_prepared_transactions costs ~600 bytes of shared
memory
# per transaction slot, plus lock space (see max_locks_per_transaction).
work_mem = 204800                       # min 64, size in KB
maintenance_work_mem = 323840           # min 1024, size in KB
#max_stack_depth = 2048                 # min 100, size in KB

# - Free Space Map -

max_fsm_pages = 8000000                 # min max_fsm_relations*16, 6 bytes
each
max_fsm_relations = 10000               # min 100, ~70 bytes each

# - Kernel Resource Usage -

#max_files_per_process = 1000           # min 25
#preload_libraries = ''

# - Cost-Based Vacuum Delay -

#vacuum_cost_delay = 0                  # 0-1000 milliseconds
#vacuum_cost_page_hit = 1               # 0-10000 credits
#vacuum_cost_page_miss = 10             # 0-10000 credits
#vacuum_cost_page_dirty = 20            # 0-10000 credits
#vacuum_cost_limit = 200                # 0-10000 credits

# - Background writer -

#bgwriter_delay = 200                   # 10-10000 milliseconds between
rounds
#bgwriter_lru_percent = 1.0             # 0-100% of LRU buffers
scanned/round
bgwriter_lru_maxpages = 100             # 0-1000 buffers max written/round
#bgwriter_all_percent = 0.333           # 0-100% of all buffers
scanned/round
bgwriter_all_maxpages = 100             # 0-1000 buffers max written/round


#---------------------------------------------------------------------------

# WRITE AHEAD LOG
#---------------------------------------------------------------------------


# - Settings -

fsync = off                             # turns forced synchronization on or
off
#wal_sync_method = fsync                # the default is the first option
                                        # supported by the operating
system:
                                        #   open_datasync
                                        #   fdatasync
                                        #   fsync
                                        #   fsync_writethrough
                                        #   open_sync
full_page_writes = off                  # recover from partial page writes
wal_buffers = 200                       # min 4, 8KB each
#commit_delay = 0                       # range 0-100000, in microseconds
#commit_siblings = 5                    # range 1-1000

# - Checkpoints -

checkpoint_segments = 30                # in logfile segments, min 1, 16MB
each
#checkpoint_timeout = 300               # range 30-3600, in seconds
#checkpoint_warning = 30                # in seconds, 0 is off

# - Archiving -

#archive_command = ''                   # command to use to archive a
logfile
                                        # segment


#---------------------------------------------------------------------------

# QUERY TUNING
#---------------------------------------------------------------------------


# - Planner Method Configuration -

#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_mergejoin = on
#enable_nestloop = on
#enable_seqscan = on
#enable_sort = on
#enable_tidscan = on

# - Planner Cost Constants -

#effective_cache_size = 1000            # typically 8KB each
#random_page_cost = 4                   # units are one sequential page
fetch
                                        # cost
#cpu_tuple_cost = 0.01                  # (same)
#cpu_index_tuple_cost = 0.001           # (same)
#cpu_operator_cost = 0.0025             # (same)

# - Genetic Query Optimizer -

#geqo = on
#geqo_threshold = 12
#geqo_effort = 5                        # range 1-10
#geqo_pool_size = 0                     # selects default based on effort
#geqo_generations = 0                   # selects default based on effort
#geqo_selection_bias = 2.0              # range 1.5-2.0

# - Other Planner Options -

#default_statistics_target = 10         # range 1-1000
#constraint_exclusion = off
#from_collapse_limit = 8
#join_collapse_limit = 8                # 1 disables collapsing of explicit

                                        # JOINs


#---------------------------------------------------------------------------

# ERROR REPORTING AND LOGGING
#---------------------------------------------------------------------------


# - Where to Log -

#log_destination = 'stderr'             # Valid values are combinations of
                                        # stderr, syslog and eventlog,
                                        # depending on platform.

# This is used when logging to stderr:
redirect_stderr = on                    # Enable capturing of stderr into
log
                                        # files

# These are only used if redirect_stderr is on:
log_directory = 'pg_log'                # Directory where log files are
written
                                        # Can be absolute or relative to
PGDATA
#log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # Log file name pattern.
                                        # Can include strftime() escapes
log_truncate_on_rotation = on           # If on, any existing log file of
the same
                                        # name as the new log file will be
                                        # truncated rather than appended to.
But
                                        # such truncation only occurs on
                                        # time-driven rotation, not on
restarts
                                        # or size-driven rotation. Default
is
                                        # off, meaning append to existing
files
                                        # in all cases.
log_rotation_age = 1440                 # Automatic rotation of logfiles
will
                                        # happen after so many minutes.  0
to
                                        # disable.
log_rotation_size = 0                   # Automatic rotation of logfiles
will
                                        # happen after so many kilobytes of
log
                                        # output.  0 to disable.

# These are relevant when logging to syslog:
#syslog_facility = 'LOCAL0'
#syslog_ident = 'postgres'


# - When to Log -

#client_min_messages = notice           # Values, in order of decreasing
detail:
                                        #   debug5
                                        #   debug4
                                        #   debug3
                                        #   debug2
                                        #   debug1
                                        #   log
                                        #   notice
                                        #   warning
                                        #   error

#log_min_messages = notice              # Values, in order of decreasing
detail:
                                        #   debug5
                                        #   debug4
                                        #   debug3
                                        #   debug2
                                        #   debug1
                                        #   info
                                        #   notice
                                        #   warning
                                        #   error
                                        #   log
                                        #   fatal
                                        #   panic

#log_error_verbosity = default          # terse, default, or verbose
messages

#log_min_error_statement = panic        # Values in order of increasing
severity:
                                        #   debug5
                                        #   debug4
                                        #   debug3
                                        #   debug2
                                        #   debug1
                                        #   info
                                        #   notice
                                        #   warning
                                        #   error
                                        #   panic(off)

#log_min_duration_statement = -1        # -1 is disabled, 0 logs all
statements
                                        # and their durations, in
milliseconds.

#silent_mode = off                      # DO NOT USE without syslog or
                                        # redirect_stderr

# - What to Log -

#debug_print_parse = off
#debug_print_rewritten = off
#debug_print_plan = off
#debug_pretty_print = off
#log_connections = off
#log_disconnections = off
#log_duration = off
#log_line_prefix = ''                   # Special values:
                                        #   %u = user name
                                        #   %d = database name
                                        #   %r = remote host and port
                                        #   %h = remote host
                                        #   %p = PID
                                        #   %t = timestamp (no
milliseconds)
                                        #   %m = timestamp with
milliseconds
                                        #   %i = command tag
                                        #   %c = session id
                                        #   %l = session line number
                                        #   %s = session start timestamp
                                        #   %x = transaction id
                                        #   %q = stop here in non-session
                                        #        processes
                                        #   %% = '%'
                                        # e.g. '<%u%%%d> '
#log_statement = 'none'                 # none, mod, ddl, all
#log_hostname = off


#---------------------------------------------------------------------------

# RUNTIME STATISTICS
#---------------------------------------------------------------------------


# - Statistics Monitoring -

#log_parser_stats = off
#log_planner_stats = off
#log_executor_stats = off
#log_statement_stats = off

# - Query/Index Statistics Collector -

#stats_start_collector = on
#stats_command_string = off
#stats_block_level = off
#stats_row_level = off
#stats_reset_on_server_start = off


#---------------------------------------------------------------------------

# AUTOVACUUM PARAMETERS
#---------------------------------------------------------------------------


#autovacuum = off                       # enable autovacuum subprocess?
#autovacuum_naptime = 60                # time between autovacuum runs, in
secs
#autovacuum_vacuum_threshold = 1000     # min # of tuple updates before
                                        # vacuum
#autovacuum_analyze_threshold = 500     # min # of tuple updates before
                                        # analyze
#autovacuum_vacuum_scale_factor = 0.4   # fraction of rel size before
                                        # vacuum
#autovacuum_analyze_scale_factor = 0.2  # fraction of rel size before
                                        # analyze
#autovacuum_vacuum_cost_delay = -1      # default vacuum cost delay for
                                        # autovac, -1 means use
                                        # vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1      # default vacuum cost limit for
                                        # autovac, -1 means use
                                        # vacuum_cost_limit


#---------------------------------------------------------------------------

# CLIENT CONNECTION DEFAULTS
#---------------------------------------------------------------------------


# - Statement Behavior -

#search_path = '$user,public'           # schema names
#default_tablespace = ''                # a tablespace name, '' uses
                                        # the default
#check_function_bodies = on
#default_transaction_isolation = 'read committed'
#default_transaction_read_only = off
#statement_timeout = 0                  # 0 is disabled, in milliseconds

# - Locale and Formatting -

#datestyle = 'iso, mdy'
#timezone = unknown                     # actually, defaults to TZ
                                        # environment setting
#australian_timezones = off
#extra_float_digits = 0                 # min -15, max 2
#client_encoding = sql_ascii            # actually, defaults to database
                                        # encoding

# These settings are initialized by initdb -- they might be changed
lc_messages = 'en_US.UTF-8'                     # locale for system error
message
                                        # strings
lc_monetary = 'en_US.UTF-8'                     # locale for monetary
formatting
lc_numeric = 'en_US.UTF-8'                      # locale for number
formatting
lc_time = 'en_US.UTF-8'                         # locale for time
formatting

# - Other Defaults -

#explain_pretty_print = on
#dynamic_library_path = '$libdir'


#---------------------------------------------------------------------------

# LOCK MANAGEMENT
#---------------------------------------------------------------------------


#deadlock_timeout = 1000                # in milliseconds
#max_locks_per_transaction = 64         # min 10
# note: each lock table slot uses ~220 bytes of shared memory, and there
are
# max_locks_per_transaction * (max_connections + max_prepared_transactions)
# lock table slots.


#---------------------------------------------------------------------------

# VERSION/PLATFORM COMPATIBILITY
#---------------------------------------------------------------------------


# - Previous Postgres Versions -

#add_missing_from = off
#regex_flavor = advanced                # advanced, extended, or basic
#sql_inheritance = on
#default_with_oids = off
#escape_string_warning = off

# - Other Platforms & Clients -

#transform_null_equals = off


#---------------------------------------------------------------------------

# CUSTOMIZED OPTIONS
#---------------------------------------------------------------------------


#custom_variable_classes = ''           # list of custom variable class
names