###########################################################################
#                         jvm-server.options                              #
#                                                                         #
# - all flags defined here will be used by cassandra to startup the JVM   #
# - one flag should be specified per line                                 #
# - lines that do not start with '-' will be ignored                      #
# - only static flags are accepted (no variables or parameters)           #
# - dynamic flags will be appended to these on cassandra-env              #
#                                                                         #
# See jvm8-server.options and jvm11-server.options for Java version       #
# specific options.                                                       #
###########################################################################

######################
# STARTUP PARAMETERS #
######################

# Uncomment any of the following properties to enable specific startup parameters

# In a multi-instance deployment, multiple Cassandra instances will independently assume that all
# CPU processors are available to it. This setting allows you to specify a smaller set of processors
# and perhaps have affinity.
#-Dcassandra.available_processors=number_of_processors

# The directory location of the cassandra.yaml file.
#-Dcassandra.config=directory

# Sets the initial partitioner token for a node the first time the node is started.
#-Dcassandra.initial_token=token

# Set to false to start Cassandra on a node but not have the node join the cluster.
#-Dcassandra.join_ring=true|false

# Set to false to clear all gossip state for the node on restart. Use when you have changed node
# information in cassandra.yaml (such as listen_address).
#-Dcassandra.load_ring_state=true|false

# Enable pluggable metrics reporter. See Pluggable metrics reporting in Cassandra 2.0.2.
#-Dcassandra.metricsReporterConfigFile=file

# Set the port on which the CQL native transport listens for clients. (Default: 9042)
#-Dcassandra.native_transport_port=port

# Overrides the partitioner. (Default: org.apache.cassandra.dht.Murmur3Partitioner)
#-Dcassandra.partitioner=partitioner

# To replace a node that has died, restart a new node in its place specifying the address of the
# dead node. The new node must not have any data in its data directory, that is, it must be in the
# same state as before bootstrapping.
#-Dcassandra.replace_address=listen_address or broadcast_address of dead node

# Allow restoring specific tables from an archived commit log.
#-Dcassandra.replayList=table

# Allows overriding of the default RING_DELAY (30000ms), which is the amount of time a node waits
# before joining the ring.
#-Dcassandra.ring_delay_ms=ms

# Set the SSL port for encrypted communication. (Default: 7001)
#-Dcassandra.ssl_storage_port=port

# Set the port for inter-node communication. (Default: 7000)
#-Dcassandra.storage_port=port

# Set the default location for the trigger JARs. (Default: conf/triggers)
#-Dcassandra.triggers_dir=directory

# For testing new compaction and compression strategies. It allows you to experiment with different
# strategies and benchmark write performance differences without affecting the production workload. 
#-Dcassandra.write_survey=true

# To disable configuration via JMX of auth caches (such as those for credentials, permissions and
# roles). This will mean those config options can only be set (persistently) in cassandra.yaml
# and will require a restart for new values to take effect.
#-Dcassandra.disable_auth_caches_remote_configuration=true

# To disable dynamic calculation of the page size used when indexing an entire partition (during
# initial index build/rebuild). If set to true, the page size will be fixed to the default of
# 10000 rows per page.
#-Dcassandra.force_default_indexing_page_size=true

# Imposes an upper bound on hint lifetime below the normal min gc_grace_seconds
#-Dcassandra.maxHintTTL=max_hint_ttl_in_seconds

########################
# GENERAL JVM SETTINGS #
########################

# enable assertions. highly suggested for correct application functionality.
-ea

# disable assertions for net.openhft.** because it runs out of memory by design
# if enabled and run for more than just brief testing
-da:net.openhft...

# enable thread priorities, primarily so we can give periodic tasks
# a lower priority to avoid interfering with client workload
-XX:+UseThreadPriorities

# Enable heap-dump if there's an OOM
-XX:+HeapDumpOnOutOfMemoryError

# Per-thread stack size.
-Xss256k

# Make sure all memory is faulted and zeroed on startup.
# This helps prevent soft faults in containers and makes
# transparent hugepage allocation more effective.
-XX:+AlwaysPreTouch

# Enable thread-local allocation blocks and allow the JVM to automatically
# resize them at runtime.
-XX:+UseTLAB
-XX:+ResizeTLAB
-XX:+UseNUMA

# http://www.evanjones.ca/jvm-mmap-pause.html
-XX:+PerfDisableSharedMem

# Prefer binding to IPv4 network intefaces (when net.ipv6.bindv6only=1). See
# http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6342561 (short version:
# comment out this entry to enable IPv6 support).
-Djava.net.preferIPv4Stack=true

### Debug options

# uncomment to enable flight recorder
#-XX:+UnlockCommercialFeatures
#-XX:+FlightRecorder

# uncomment to have Cassandra JVM listen for remote debuggers/profilers on port 1414
#-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=1414

# uncomment to have Cassandra JVM log internal method compilation (developers only)
#-XX:+UnlockDiagnosticVMOptions
#-XX:+LogCompilation

#################
# HEAP SETTINGS #
#################

# Heap size is automatically calculated by cassandra-env based on this
# formula: max(min(1/2 ram, 1024MB), min(1/4 ram, 8GB))
# That is:
# - calculate 1/2 ram and cap to 1024MB
# - calculate 1/4 ram and cap to 8192MB
# - pick the max
#
# For production use you may wish to adjust this for your environment.
# If that's the case, uncomment the -Xmx and Xms options below to override the
# automatic calculation of JVM heap memory.
#
# It is recommended to set min (-Xms) and max (-Xmx) heap sizes to
# the same value to avoid stop-the-world GC pauses during resize, and
# so that we can lock the heap in memory on startup to prevent any
# of it from being swapped out.
#-Xms4G
#-Xmx4G

# Young generation size is automatically calculated by cassandra-env
# based on this formula: min(100 * num_cores, 1/4 * heap size)
#
# The main trade-off for the young generation is that the larger it
# is, the longer GC pause times will be. The shorter it is, the more
# expensive GC will be (usually).
#
# It is not recommended to set the young generation size if using the
# G1 GC, since that will override the target pause-time goal.
# More info: http://www.oracle.com/technetwork/articles/java/g1gc-1984535.html
#
# The example below assumes a modern 8-core+ machine for decent
# times. If in doubt, and if you do not particularly want to tweak, go
# 100 MB per physical CPU core.
#-Xmn800M

###################################
# EXPIRATION DATE OVERFLOW POLICY #
###################################

# Defines how to handle INSERT requests with TTL exceeding the maximum supported expiration date:
# * REJECT: this is the default policy and will reject any requests with expiration date timestamp after 2038-01-19T03:14:06+00:00.
# * CAP: any insert with TTL expiring after 2038-01-19T03:14:06+00:00 will expire on 2038-01-19T03:14:06+00:00 and the client will receive a warning.
# * CAP_NOWARN: same as previous, except that the client warning will not be emitted.
#
#-Dcassandra.expiration_date_overflow_policy=REJECT