I am basically having the same issue as this person,
I am on Graylog 3.0 but I was getting this issue on 2.5 too, the server is a physical server in our data centre (Intel(R) Xeon(R) CPU E5620 @ 2.40GHz with 64GB of RAM).
Server conf
############################
# GRAYLOG CONFIGURATION FILE
############################
#
# This is the Graylog configuration file. The file has to use ISO 8859-1/Latin-1 character encoding.
# Characters that cannot be directly represented in this encoding can be written using Unicode escapes
# as defined in https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.3, using the \u prefix.
# For example, \u002c.
#
# * Entries are generally expected to be a single line of the form, one of the following:
#
# propertyName=propertyValue
# propertyName:propertyValue
#
# * White space that appears between the property name and property value is ignored,
# so the following are equivalent:
#
# name=Stephen
# name = Stephen
#
# * White space at the beginning of the line is also ignored.
#
# * Lines that start with the comment characters ! or # are ignored. Blank lines are also ignored.
#
# * The property value is generally terminated by the end of the line. White space following the
# property value is not ignored, and is treated as part of the property value.
#
# * A property value can span several lines if each line is terminated by a backslash (‘\’) character.
# For example:
#
# targetCities=\
# Detroit,\
# Chicago,\
# Los Angeles
#
# This is equivalent to targetCities=Detroit,Chicago,Los Angeles (white space at the beginning of lines is ignored).
#
# * The characters newline, carriage return, and tab can be inserted with characters \n, \r, and \t, respectively.
#
# * The backslash character must be escaped as a double backslash. For example:
#
# path=c:\\docs\\doc1
#
# If you are running more than one instances of Graylog server you have to select one of these
# instances as master. The master will perform some periodical tasks that non-masters won't perform.
is_master = true
# The auto-generated node ID will be stored in this file and read after restarts. It is a good idea
# to use an absolute file path here if you are starting Graylog server from init scripts or similar.
node_id_file = /etc/graylog/server/node-id
# You MUST set a secret to secure/pepper the stored user passwords here. Use at least 64 characters.
# Generate one by using for example: pwgen -N 1 -s 96
password_secret =
# The default root user is named 'admin'
#root_username = admin
# You MUST specify a hash password for the root user (which you only need to initially set up the
# system and in case you lose connectivity to your authentication backend)
# This password cannot be changed using the API or via the web interface. If you need to change it,
# modify it in this file.
# Create one by using for example: echo -n yourpassword | shasum -a 256
# and put the resulting hash value into the following line
root_password_sha2 =
# The email address of the root user.
# Default is empty
#root_email = ""
# The time zone setting of the root user. See http://www.joda.org/joda-time/timezones.html for a list of valid time zones.
# Default is UTC
#root_timezone = UTC
# Set plugin directory here (relative or absolute)
plugin_dir = /usr/share/graylog-server/plugin
###############
# HTTP settings
###############
#### HTTP bind address
#
# The network interface used by the Graylog HTTP interface.
#
# This network interface must be accessible by all Graylog nodes in the cluster and by all clients
# using the Graylog web interface.
#
# If the port is omitted, Graylog will use port 9000 by default.
#
# Default: 127.0.0.1:9000
#http_bind_address = 127.0.0.1:9000
#http_bind_address = [2001:db8::1]:9000
http_bind_address = 10.3.11.250:9000
#### HTTP publish URI
#
# The HTTP URI of this Graylog node which is used to communicate with the other Graylog nodes in the cluster and by all
# clients using the Graylog web interface.
#
# The URI will be published in the cluster discovery APIs, so that other Graylog nodes will be able to find and connect to this Graylog node.
#
# This configuration setting has to be used if this Graylog node is available on another network interface than $http_bind_address,
# for example if the machine has multiple network interfaces or is behind a NAT gateway.
#
# If $http_bind_address contains a wildcard IPv4 address (0.0.0.0), the first non-loopback IPv4 address of this machine will be used.
# This configuration setting *must not* contain a wildcard address!
#
# Default: http://$http_bind_address/
http_publish_uri = http://10.3.11.250:9000/
#### External Graylog URI
#
# The public URI of Graylog which will be used by the Graylog web interface to communicate with the Graylog REST API.
#
# The external Graylog URI usually has to be specified, if Graylog is running behind a reverse proxy or load-balancer
# and it will be used to generate URLs addressing entities in the Graylog REST API (see $http_bind_address).
#
# When using Graylog Collector, this URI will be used to receive heartbeat messages and must be accessible for all collectors.
#
# This setting can be overriden on a per-request basis with the "X-Graylog-Server-URL" HTTP request header.
#
# Default: $http_publish_uri
#http_external_uri = 10.3.11.250/
#### Enable CORS headers for HTTP interface
#
# This is necessary for JS-clients accessing the server directly.
# If these are disabled, modern browsers will not be able to retrieve resources from the server.
# This is enabled by default. Uncomment the next line to disable it.
#http_enable_cors = false
#### Enable GZIP support for HTTP interface
#
# This compresses API responses and therefore helps to reduce
# overall round trip times. This is enabled by default. Uncomment the next line to disable it.
#http_enable_gzip = false
# The maximum size of the HTTP request headers in bytes.
#http_max_header_size = 8192
# The size of the thread pool used exclusively for serving the HTTP interface.
#http_thread_pool_size = 16
################
# HTTPS settings
################
#### Enable HTTPS support for the HTTP interface
#
# This secures the communication with the HTTP interface with TLS to prevent request forgery and eavesdropping.
#
# Default: false
#http_enable_tls = true
# The X.509 certificate chain file in PEM format to use for securing the HTTP interface.
#http_tls_cert_file = /path/to/graylog.crt
# The PKCS#8 private key file in PEM format to use for securing the HTTP interface.
#http_tls_key_file = /path/to/graylog.key
# The password to unlock the private key used for securing the HTTP interface.
#http_tls_key_password = secret
# Comma separated list of trusted proxies that are allowed to set the client address with X-Forwarded-For
# header. May be subnets, or hosts.
#trusted_proxies = 127.0.0.1/32, 0:0:0:0:0:0:0:1/128
# List of Elasticsearch hosts Graylog should connect to.
# Need to be specified as a comma-separated list of valid URIs for the http ports of your elasticsearch nodes.
# If one or more of your elasticsearch hosts require authentication, include the credentials in each node URI that
# requires authentication.
#
Default: http://10.3.11.250:9200
#elasticsearch_hosts = http://elasticsearch:9200
# Maximum amount of time to wait for successfull connection to Elasticsearch HTTP port.
#
# Default: 10 Seconds
#elasticsearch_connect_timeout = 10s
# Maximum amount of time to wait for reading back a response from an Elasticsearch server.
#
# Default: 60 seconds
#elasticsearch_socket_timeout = 60s
# Maximum idle time for an Elasticsearch connection. If this is exceeded, this connection will
# be tore down.
#
# Default: inf
#elasticsearch_idle_timeout = -1s
# Maximum number of total connections to Elasticsearch.
#
# Default: 20
#elasticsearch_max_total_connections = 20
# Maximum number of total connections per Elasticsearch route (normally this means per
# elasticsearch server).
#
# Default: 2
#elasticsearch_max_total_connections_per_route = 2
# Maximum number of times Graylog will retry failed requests to Elasticsearch.
#
# Default: 2
#elasticsearch_max_retries = 2
# Enable automatic Elasticsearch node discovery through Nodes Info,
# see https://www.elastic.co/guide/en/elasticsearch/reference/5.4/cluster-nodes-info.html
#
# WARNING: Automatic node discovery does not work if Elasticsearch requires authentication, e. g. with Shield.
#
# Default: false
#elasticsearch_discovery_enabled = true
# Filter for including/excluding Elasticsearch nodes in discovery according to their custom attributes,
# see https://www.elastic.co/guide/en/elasticsearch/reference/5.4/cluster.html#cluster-nodes
#
# Default: empty
#elasticsearch_discovery_filter = rack:42
# Frequency of the Elasticsearch node discovery.
#
# Default: 30s
# elasticsearch_discovery_frequency = 30s
# Enable payload compression for Elasticsearch requests.
#
# Default: false
#elasticsearch_compression_enabled = true
# Disable checking the version of Elasticsearch for being compatible with this Graylog release.
# WARNING: Using Graylog with unsupported and untested versions of Elasticsearch may lead to data loss!
#elasticsearch_disable_version_check = true
# Disable message retention on this node, i. e. disable Elasticsearch index rotation.
#no_retention = false
# Do you want to allow searches with leading wildcards? This can be extremely resource hungry and should only
# be enabled with care. See also: http://docs.graylog.org/en/2.1/pages/queries.html
allow_leading_wildcard_searches = false
# Do you want to allow searches to be highlighted? Depending on the size of your messages this can be memory hungry and
# should only be enabled after making sure your Elasticsearch cluster has enough memory.
allow_highlighting = false
# Global request timeout for Elasticsearch requests (e. g. during search, index creation, or index time-range
# calculations) based on a best-effort to restrict the runtime of Elasticsearch operations.
# Default: 1m
#elasticsearch_request_timeout = 1m
# Global timeout for index optimization (force merge) requests.
# Default: 1h
#elasticsearch_index_optimization_timeout = 1h
# Maximum number of concurrently running index optimization (force merge) jobs.
# If you are using lots of different index sets, you might want to increase that number.
# Default: 20
#elasticsearch_index_optimization_jobs = 20
# Time interval for index range information cleanups. This setting defines how often stale index range information
# is being purged from the database.
# Default: 1h
#index_ranges_cleanup_interval = 1h
# Batch size for the Elasticsearch output. This is the maximum (!) number of messages the Elasticsearch output
# module will get at once and write to Elasticsearch in a batch call. If the configured batch size has not been
# reached within output_flush_interval seconds, everything that is available will be flushed at once. Remember
# that every outputbuffer processor manages its own batch and performs its own batch write calls.
# ("outputbuffer_processors" variable)
output_batch_size = 500
# Flush interval (in seconds) for the Elasticsearch output. This is the maximum amount of time between two
# batches of messages written to Elasticsearch. It is only effective at all if your minimum number of messages
# for this time period is less than output_batch_size * outputbuffer_processors.
output_flush_interval = 1
# As stream outputs are loaded only on demand, an output which is failing to initialize will be tried over and
# over again. To prevent this, the following configuration options define after how many faults an output will
# not be tried again for an also configurable amount of seconds.
output_fault_count_threshold = 5
output_fault_penalty_seconds = 30
# The number of parallel running processors.
# Raise this number if your buffers are filling up.
processbuffer_processors = 5
outputbuffer_processors = 3
# The following settings (outputbuffer_processor_*) configure the thread pools backing each output buffer processor.
# See https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ThreadPoolExecutor.html for technical details
# When the number of threads is greater than the core (see outputbuffer_processor_threads_core_pool_size),
# this is the maximum time in milliseconds that excess idle threads will wait for new tasks before terminating.
# Default: 5000
#outputbuffer_processor_keep_alive_time = 5000
# The number of threads to keep in the pool, even if they are idle, unless allowCoreThreadTimeOut is set
# Default: 3
#outputbuffer_processor_threads_core_pool_size = 3
# The maximum number of threads to allow in the pool
# Default: 30
#outputbuffer_processor_threads_max_pool_size = 30
# UDP receive buffer size for all message inputs (e. g. SyslogUDPInput).
#udp_recvbuffer_sizes = 1048576
# Wait strategy describing how buffer processors wait on a cursor sequence. (default: sleeping)
# Possible types:
# - yielding
# Compromise between performance and CPU usage.
# - sleeping
# Compromise between performance and CPU usage. Latency spikes can occur after quiet periods.
# - blocking
# High throughput, low latency, higher CPU usage.
# - busy_spinning
# Avoids syscalls which could introduce latency jitter. Best when threads can be bound to specific CPU cores.
processor_wait_strategy = blocking
# Size of internal ring buffers. Raise this if raising outputbuffer_processors does not help anymore.
# For optimum performance your LogMessage objects in the ring buffer should fit in your CPU L3 cache.
# Must be a power of 2. (512, 1024, 2048, ...)
ring_size = 65536
inputbuffer_ring_size = 65536
inputbuffer_processors = 2
inputbuffer_wait_strategy = blocking
# Enable the disk based message journal.
message_journal_enabled = true
# The directory which will be used to store the message journal. The directory must me exclusively used by Graylog and
# must not contain any other files than the ones created by Graylog itself.
#
# ATTENTION:
# If you create a seperate partition for the journal files and use a file system creating directories like 'lost+found'
# in the root directory, you need to create a sub directory for your journal.
# Otherwise Graylog will log an error message that the journal is corrupt and Graylog will not start.
message_journal_dir = /var/lib/graylog-server/journal
# Journal hold messages before they could be written to Elasticsearch.
# For a maximum of 12 hours or 5 GB whichever happens first.
# During normal operation the journal will be smaller.
#message_journal_max_age = 12h
#message_journal_max_size = 5gb
#message_journal_flush_age = 1m
#message_journal_flush_interval = 1000000
#message_journal_segment_age = 1h
#message_journal_segment_size = 100mb
# Number of threads used exclusively for dispatching internal events. Default is 2.
#async_eventbus_processors = 2
# How many seconds to wait between marking node as DEAD for possible load balancers and starting the actual
# shutdown process. Set to 0 if you have no status checking load balancers in front.
lb_recognition_period_seconds = 3
# Journal usage percentage that triggers requesting throttling for this server node from load balancers. The feature is
# disabled if not set.
#lb_throttle_threshold_percentage = 95
# Every message is matched against the configured streams and it can happen that a stream contains rules which
# take an unusual amount of time to run, for example if its using regular expressions that perform excessive backtracking.
# This will impact the processing of the entire server. To keep such misbehaving stream rules from impacting other
# streams, Graylog limits the execution time for each stream.
# The default values are noted below, the timeout is in milliseconds.
# If the stream matching for one stream took longer than the timeout value, and this happened more than "max_faults" times
# that stream is disabled and a notification is shown in the web interface.
#stream_processing_timeout = 2000
#stream_processing_max_faults = 3
# Length of the interval in seconds in which the alert conditions for all streams should be checked
# and alarms are being sent.
#alert_check_interval = 60
# Since 0.21 the Graylog server supports pluggable output modules. This means a single message can be written to multiple
# outputs. The next setting defines the timeout for a single output module, including the default output module where all
# messages end up.
#
# Time in milliseconds to wait for all message outputs to finish writing a single message.
#output_module_timeout = 10000
# Time in milliseconds after which a detected stale master node is being rechecked on startup.
#stale_master_timeout = 2000
# Time in milliseconds which Graylog is waiting for all threads to stop on shutdown.
#shutdown_timeout = 30000
# MongoDB connection string
# See https://docs.mongodb.com/manual/reference/connection-string/ for details
mongodb_uri = mongodb://localhost/graylog
# Authenticate against the MongoDB server
#mongodb_uri = mongodb://grayloguser:secret@localhost:27017/graylog
# Use a replica set instead of a single host
#mongodb_uri = mongodb://grayloguser:secret@localhost:27017,localhost:27018,localhost:27019/graylog
# Increase this value according to the maximum connections your MongoDB server can handle from a single client
# if you encounter MongoDB connection problems.
mongodb_max_connections = 1000
# Number of threads allowed to be blocked by MongoDB connections multiplier. Default: 5
# If mongodb_max_connections is 100, and mongodb_threads_allowed_to_block_multiplier is 5,
# then 500 threads can block. More than that and an exception will be thrown.
# http://api.mongodb.com/java/current/com/mongodb/MongoOptions.html#threadsAllowedToBlockForConnectionMultiplier
mongodb_threads_allowed_to_block_multiplier = 5
# Drools Rule File (Use to rewrite incoming log messages)
# See: http://docs.graylog.org/en/2.1/pages/drools.html
#rules_file = /etc/graylog/server/rules.drl
# Email transport
#transport_email_enabled = false
#transport_email_hostname = mail.example.com
#transport_email_port = 587
#transport_email_use_auth = true
#transport_email_use_tls = true
#transport_email_use_ssl = true
#transport_email_auth_username = you@example.com
#transport_email_auth_password = secret
#transport_email_subject_prefix = [graylog]
#transport_email_from_email = graylog@example.com
# Specify and uncomment this if you want to include links to the stream in your stream alert mails.
# This should define the fully qualified base url to your web interface exactly the same way as it is accessed by your users.
#transport_email_web_interface_url = https://graylog.example.com
# The default connect timeout for outgoing HTTP connections.
# Values must be a positive duration (and between 1 and 2147483647 when converted to milliseconds).
# Default: 5s
#http_connect_timeout = 5s
# The default read timeout for outgoing HTTP connections.
# Values must be a positive duration (and between 1 and 2147483647 when converted to milliseconds).
# Default: 10s
#http_read_timeout = 10s
# The default write timeout for outgoing HTTP connections.
# Values must be a positive duration (and between 1 and 2147483647 when converted to milliseconds).
# Default: 10s
#http_write_timeout = 10s
# HTTP proxy for outgoing HTTP connections
#http_proxy_uri =
# The threshold of the garbage collection runs. If GC runs take longer than this threshold, a system notification
# will be generated to warn the administrator about possible problems with the system. Default is 1 second.
#gc_warning_threshold = 1s
# Connection timeout for a configured LDAP server (e. g. ActiveDirectory) in milliseconds.
#ldap_connection_timeout = 2000
# Disable the use of SIGAR for collecting system stats
#disable_sigar = false
# The default cache time for dashboard widgets. (Default: 10 seconds, minimum: 1 second)
#dashboard_widget_default_cache_time = 10s
# Automatically load content packs in "content_packs_dir" on the first start of Graylog.
#content_packs_loader_enabled = true
# The directory which contains content packs which should be loaded on the first start of Graylog.
content_packs_dir = /usr/share/graylog-server/contentpacks
# A comma-separated list of content packs (files in "content_packs_dir") which should be applied on
# the first start of Graylog.
# Default: empty
content_packs_auto_load = grok-patterns.json
# For some cluster-related REST requests, the node must query all other nodes in the cluster. This is the maximum number
# of threads available for this. Increase it, if '/cluster/*' requests take long to complete.
# Should be http_thread_pool_size * average_cluster_size if you have a high number of concurrent users.
proxied_requests_thread_pool_size = 32
Server is in our DC which we have a site to site VPN with, the odd issue is that when the alerts calm down and the messages slow down, it starts to work.
Otherwise it’s fine.
