Command-Line Options

Zing Command-Line Options

 
-XX:ProfileLogOut=<directory>/profileLogOut<timestamp>.profile
-Xlog:gc,safepoint:<directory>/gc-log<timestamp>.log::filecount=5,filesize=50M
-XX:SafepointWaitTimeProfilerLog=<directory>/safepoint-profile<timestamp>.log
-XX:SafepointProfilerThresholdMS=5
-XX:+PrintCompilation
-XX:+TraceDeoptimization
-XX:-DisplayVMOutput
-XX:LogFile=<directory>/hotspot<timestamp>.log
-XX:+LogVMOutput

 
-XX:+FlightRecorder
-XX:StartFlightRecording=filename=<directory>/jfr<timestamp>.jfr
-Xlog:gc*,safepoint:<directory>/gc-log-<timestamp>.log::filecount=5,filesize=50M // OVERRIDDEN

 
-XX:FalconIRDumpRoot=<directory>
-XX:FalconDumpIRToDiskOf=*
-XX:+PrintInlining
-Xlog:gc*,safepoint:<directory>/gc-log-<timestamp>.log::filecount=0  // OVERRIDDEN - ATTENTION: no limit to file size

Intrinsic Options

Intrinsics are hand-tuned machine code integrated into the JVM for some numeric algorithms like BigInteger, AES encryption, CRC checksum calculations, and SSE/AVM opcodes. Most are turned on by default. To see a list of all adjustable intrinsic options of the current Zing JVM and their default values, run the following command:

 
/opt/zing/zing-jdk1.8.0-<version>/bin/java -XX:+PrintFlagsFinal -version 2>&1 | grep Intrinsic

Prime Memory and CPU Footprint Control

Native Memory Tracking Options

These options are useful to analyze usage of memory outside the Java heap and ZST memory for NIO, thread stacks.

 
LD_PRELOAD=$JAVA_HOME/etc/zing/lib/libnmt_hooks.so

Defensive Heap Shrinking

Defensive heap shrinking, introduced in Azul Prime 24.02.0.0, dynamically reduces committed Java heap in order to avoid Out-of-memory (OOM) errors in container environments, which ordinarily lead to OOM kills and crashes.

Setting VMFootprintLevel to L, M or S enables UseDefensiveHeapShrinking with M and S setting DefensiveHeapShrinkingXmxSacrificePercent to 20 and L setting DefensiveHeapShrinkingXmxSacrificePercent to 10.

Code Cache Use Optimization Options

Monitor Cache Use Optimization Options

Thread Local Allocation Buffer (TLAB) Use Optimization Options

Zing in the Non-ZST Mode Options (available since Azul Zing 19.06.0.0)

Garbage Collector Options

Advanced Miscellaneous Options

|Header |Description |applicationTime |Time called |Bytes |Bytes consumed |classInitTime |Time called |classLinkedTime |Time called |classVerifyTime |Time called |GCC |GC cause |GCT |Both generation collectors total GC time |JavaHeapPercentUsed |Percent of memory used by Java heap |JHMX |Java heap Xmx value |Loaded |Processes loaded |LGCC |Last GC cause |NGC |New generation GC count |NGCT |New generation GC time (concurrent time the collector is running) |OGC |Old generation GC count (at that instant) |OGCT |Old generation GC time (concurrent time the collector is running) |NGU |New generation use (at that instant) |OGU |Old generation use (at that instant) |PGU |Permanent generation use |safepointSyncTime |Time called |safepointTime |Time called |sun.cls.time |Time called |Time |Elapsed time |Unloaded |Processes unloaded |vmOperationTime |Time called

|Command-Line Option |Description |Default

|-XX:[+/-]DumpMiniCore a|This option creates significantly smaller Zing core files. This option is specified through the Java application launch command and applied to the runtime Java application. It is not applied to the Zing host machine. When you use this option:

|Command-Line Option |Description |Default

|-XX:[+/-]UseRTMLocking a|Enables speculative locking. |false

|-XX:[+/-]RTMHeuristic a|Enables (Restricted Transactional Memory) RTM heuristics. |true

|-XX:RTMAbortRatio=<threshold value> a|Threshold value for RTM heuristics. If aborted or attempted transactions ratio goes beyond this limit for a monitor then speculation is disabled for that monitor. |50

|-XX:RTMRetryCount=<attempts> a|Number of times speculation is attempted on a monitor, per lock acquisition. Fewer, or no attempts will be made if internal heuristic disables speculation on the monitor. |5

|-XX:LockingMode=<1,2> a|JDK 25 implements a new lightweight locking scheme. To use the legacy Zing locking scheme in JDK 25, you can use the command line option -XX:LockingMode=1. The legacy locking scheme, -XX:LockingMode=1, remains the default for JDK 8, 11, 17 and 21. |2 in JDK 25+, 1 in all previous JDK versions.

|Command-Line Option |Description |Default

|-XX:[+/-]UseFalcon a|Specifies which Tier 2 compiler should be used. The default Tier 2 compiler is Falcon. To use the C2 JIT (available until release 24.02) instead of the Falcon JIT, run the following command:

$JAVA_HOME/bin/java -XX:-UseFalcon –cp . myprog |

|-Xcompilerflags:ignore\|warn\|error a|Controls the handling of a Tier 2 compiler specific flag used when the other compiler is active. | warn

|-XX:[+/-]UseFalconOSR a|Controls the On Stack Replacement (OSR) functionality. It is not recommended to disable this option. If needed, disable it for only diagnostics purposes. | true

|-XX:Tier2OSRThreshold=<threshold value> a|Changes the threshold at which the OSR is triggered – that is loop compilation by the Tier 2 compiler.

The value might be decreased to improve warm-up characteristics. | 14000

|-XX:FalconCompileThreshold=<threshold value> a|Threshold value for the Falcon JIT compiler. Replaces the identical option of the C2 compiler (-XX:C2CompileThreshold) which was available until release 24.02. | 10000

|-XX:CompileCommand a|Sets the compile threshold for a particular method, used in the following way: -XX:CompileCommand="option,<Class>::<method>,FalconCompileThreshold=<threshold value>" |

|-XX:[+/-]UseKestrelC2 a|Disables Falcon and switches to the KestrelC2 compiler. |

|-XX:FalconUseAVX a|Specifies the highest supported AVX instructions set on x86/x64 CPUs. |3

|-XX:[+/-]FalconUseLegacyInliner a|This option is deprecated with no replacement starting with the release of Zing 20.02.0.0.

Switches back to the old implementation of the LLVM inliner instead of using a highly customized integrated inliner to perform inlining optimizations in Falcon compiles. |false

|-XX:FalconOptimizationLevel=<3,2,1,0> a|Controls the level of compiling optimization.

Suggested use: the default value is expected to fit most cases. However, if the CPU load at warmup is too high or warmup takes too long, there is a reason to try 1. The downside is that peak performance might be lower with that setting.

Accepts values from 0 to 3:

0 - minimal optimizations, lowest CPU consumption by Falcon (not recommended for production)

1 - reasonable optimizations and CPU time/warmup (good for production)

2 - aggressive optimizations, might expose high CPU utilization in some cases (default)

3 - turns on very aggressive optimizations known to cause long compilations and high CPU load at warmup. Ideally used with Cloud Native Compiler and ReadyNow to offset long compilation times. |2 (full Falcon)

|-XX:[+/-]FalconPreserveBoxingIdentity a|Disables aggressive optimization of boxing types (integer, double, etc.). Should only be used for applications which are found to rely on implementation defined behavior as opposed to the specified behavior of boxing routines. | false

|-XX:FalconGenerateProfilerInfo=<value> a|Specifies the method inlining detail level for performance profiling output of compiled code. Setting a lower level may help to reduce compiled code size by a few percent.

Accepts values from 0 to 2:

0 - no method inlining information is generated

1 - stack of inlined methods is generated only (default)

2 - stack of inlined methods with bytecode indices (bci) is generated | 1

|-XX:[+/-]FalconCompensateForIntelMCUForErratumSKX102 a|Introduces a nop padding based mitigation for performance regressions seen on some systems following Intel’s micro code updates in response to errata SKX102.

This option is expected to become the default in a future Zing release.

If enabled, nop padding is used to align affected branches on systems with the micro code update applied. | false

|-XX:[+/-]ForceFalconCompensateForIntelMCUForErratumSKX102 a|Forces generation of nop padded code on unaffected systems for performance validation. | false

|-XX:[+/-]FalconOptBoxing a|Enables the optimization to eliminate redundant boxing conversions. | true

|-XX:[+/-]FalconLockCoarsenOverLoop a|Enables a lock coarsening optimization for loops where the lock over a loop is coarsened. This is done by chunking the loop and coarsening the lock over the chunked loop. | true

|-XX:[+/-]FalconEnableAggressiveLockOpt a|Enables loop chunking by chunk size of 32 and performs lock coarsening over the loop. Additionally, enables lock coarsening over memory operations with monitor exit when valid to do so. | true

|-XX:[+/-]UseMultiTiering a|Enables Multi-Tiering, allowing Falcon to assign methods to more than just one Falcon optimization level, assigning methods for either mid-tier or final-tier compilation. Final-tier compilation uses the default Zing optimizations (usually Falcon optimization level 2) and mid-tier compilation uses Falcon optimization level 0. | false

|-XX:[+/-]UseUnifiedCompilerFrontend a|Allows CNC and Falcon to share the same frontend, enabling the CNC UnifiedCompiler directly in the VM. Disabling this feature tells the VM to use only the local Falcon compiler. |true

|-XX:[+/-]UnifiedCompilerFrontendReplay a|Allows us to collect more information about a crashing compile to improve reproducibility outside of the VM. Additional information is collected only for the Unified Compiler Frontend. |true

|-XX:[+/-]FalconGenerateDiscriminators a|Improves the quality of debug (DWARF) metadata received from the general assembly, which is beneficial for some diagnostic tooling. |false

|-XX:PrintHotMethodsAssemblyProfileAtExit=<number of methods> a|Prints an assembly level profiling report at the end of a run. The value specifies the number of methods to be printed. A negative value prints all methods and setting the value to 0 disables the feature. |0

|Command Line Option | Description | Default

|-XX:OptHubHost=<host>[:<port>] |<host> is the DNS name or IP address of the Optimizer Hub service. The part :<port> is optional, with port 50051 being used by default. See Connecting a JVM to Optimizer Hub for instructions to determine the correct host and port. |null

|-XX:[+/-]CNCEnableRemoteCompiler a|Allows usage of the remote compiler when Cloud Native Compiler has established a connection. Requires OptHubHost. a|false

|-XX:ProfileName=<value> a|Name of the profile to identify the application and its version, for example, my-spring-app-v1.2.3. This name allows multiple JVM instances that use the same profile name to share the Optimizer Hub functionality, such as the Cloud Native Compiler caching.

The ProfileName may only contain alphanumeric characters, and -, _, ., ~. |null

|-XX:CNCEngineUploadAddress=<host:port> a|Address to upload the compiler engine. Only needed when your Optimizer Hub has non-standard ports.

|-XX:[+/-]CNCStartWithLocalCompiler a|Enables the Falcon compiler at JVM startup and then disables it only upon failure to connect to Cloud Native Compiler. |true

|-XX:CNCLocalFallbackOptLevelLimit=<3,2,1,0> a|Limit the OptLevel for local compilations when Cloud Native Compiler is enabled.

See the Zing documentation > Falcon Compiler Options > -XX:FalconOptimizationLevel. a|3

|-XX:[+/-]CNCLocalFallbackProductivityBasedTriggering a|Enables CNC productivity-based local fallback. Other existing local fallback mechanisms like connection loss and server circuitbreaker are not controlled by this flag. Doesn’t impact telemetry collection or telemetry reporting. |true

|-XX:CNCProductivityLocalCompilationRatePerCompilerThread=<compilations per second> a|The number of compilations per second that a local compiler thread should be able to deliver when deciding to trigger local fallback.

+ Only when CNC productivity-based local fallback is enabled. |5 - Derived from FalconOptimizationLevel and CNCLocalFallbackOptLevelLimit.

|-XX:CNCProductivityMinEvaluationWindowSeconds=<time window in seconds> a|The minimum time window, in seconds, for productivity evaluation.

+ Only when CNC productivity-based local fallback is enabled. |5

|-XX:CNCProductivityMinOutstandingCompilesForEvaluation=<number of outstanding compile requests> a|The number of outstanding compile requests on the server before justifying local fallback.

+ Only when CNC productivity-based local fallback is enabled. |100

|-XX:[+/-]OptHubUseSSL a|Instructs the Zing JVM to communicate directly with Optimizer Hub without using SSL. Use this option if you installed Optimizer Hub without SSL. a|true

|-XX:OptHubSSLRootsPath=<path to cert.pem> a|Instructs the Zing JVM to use and trust a specified SSL certificate on the filesystem. a|

|-Xlog:[+/-]concomp a|Display messages describing communication with Optimizer Hub. a|false

|Command Line Option |Description |Default

|-XX:OptHubHost=<host>[:<port>] |<host> is the DNS name or IP address of the Optimizer Hub service. The part :<port> is optional, with port 50051 being used by default. See Connecting a JVM to Optimizer Hub for instructions to determine the correct host and port. |null

|-XX:ProfileName=<value> a|Name of the profile to identify the application and its version, for example, my-spring-app-v1.2.3. This name allows multiple JVM instances that use the same profile name to share the Optimizer Hub functionality, such as the use of ReadyNow Orchestrator profiles.

The ProfileName may only contain alphanumeric characters, and -, _, ., ~. |null

|-XX:[+/-]EnableRNO |Enables ReadyNow read and write to ReadyNow Orchestrator. Requires OptHubHost and uses ProfileName as the name for the profile log. a|false

| -XX:ProfileLogOut=<value> a|The ProfileLogOut enables Zing to record compilations from the current run. <value> is the name of the profile that the JVM reads as input to ReadyNow. If prefixed with opthub://, <value> is used as the profile name in ReadyNow Orchestrator. If not prefixed with opthub://, <value> is interpreted as a file path on the JVM.

|-XX:ProfileLogIn=<value> a|The ProfileLogIn allows Zing to base its decisions on the information from a previous run. The current ProfileLogIn file information is read in its entirety - before Zing starts to create a new ProfileLogOut log. <value> is the name of the profile that the JVM reads as input to ReadyNow. If prefixed with opthub://, <value> is used as the profile name in ReadyNow Orchestrator. If not prefixed with opthub://, <value> is interpreted as a file path on the JVM.

|-XX:ProfileLogOutNominationMinSize a|Indicate to server that the produced profile is eligible for promotion after specified amount of bytes recorded.

0 = any size eligible

-1 = never gets promoted |1M

|-XX:ProfileLogOutNominationMinSizePerGeneration a|Define minimum acceptable amount of bytes per generation which the profile size should reach to become eligible for promotion.

List of pair <generation>:<size>, separated by ,. For example:

 
0:1000000,1:10000000,2:25000000,3:50000000

For more information, check Understanding ReadyNow Orchestrator Generations.

|null

|-XX:ProfileLogOutNominationMinTimeSec a|When used with ReadyNow Orchestrator, the minimum time, in seconds, a profile must record before ReadyNow Orchestrator can nominate it as a candidate.

0 = any duration eligible

-1 = never gets promoted |120

|-XX:ProfileLogOutNominationMinTimeSecPerGeneration a|When used with ReadyNow Orchestrator, the minimum time, in seconds, per generation during which the profile should be recorded in order to become eligible for promotion.

List of pair <generation>:<duration>, separated by ,. For example:

 
0:100,2:150

For more information, check Understanding ReadyNow Orchestrator Generations.

a|null

|-XX:ProfileLogOutMaxNominatedGenerationCount a|When used with ReadyNow Orchestrator, specifies the maximum generation of a profile that a VM nominates.

This parameter has a server-side counterpart readyNowOrchestrator.producers.maxPromotableGeneration. The profile has to satisfy both settings to be promoted.

0 = unlimited

For more information, check Understanding ReadyNow Orchestrator Generations. |0

|-XX:ProfileLogMaxSize=<value in bytes> a|Specifies the maximum size that a ReadyNow profile log is allowed to reach. Profiles get truncated at this size, regardless of whether the application has actually been completely warmed up.

This parameter has a server-side counterpart readyNowOrchestrator.producers.maxProfileSize. The profile will be allowed to reach whatever is the smallest of both settings.

It is recommended to either not set this size explicitly, or set it generously if required, for example:

-XX:ProfileLogMaxSize=1G

0 = unlimited |0

|-XX:ProfileLogTimeLimitSeconds=<value in seconds> a|Instructs ReadyNow to stop adding to the profile log after a period of N seconds regardless of where the application has been completely warmed up. It is recommended to either not set this size explicitly, or set it generously if required.

0 = unlimited |0

|-XX:ProfileLogDumpInputToFile=<name> a|Dumps input profile to the specified path. For debugging purposes only. |null

|-XX:ProfileLogDumpOutputToFile=<name> a|Dumps output profile to the specified path. For debugging purposes only. |null

|-XX:RNOConnectionTimeoutMillis a|Timeout on establishing remote connection and timeout on interval between downloading two chunks. Specified in milliseconds. |5000

|-XX:RNOProfileFallbackInput a|Experimental feature. Local filesystem path which gets used in case no profile data is downloaded. E.g., in case of a missing connection or the requested profile name doesn’t exist on the server. |null

|-XX:ProfileLogOutVerbose a|Enables logging of verbose, optional tracing information in -XX:ProfileLogOut |true

|Command Line Option |Description |Default

|-XX:[+/-]EnableTier2CompilerBudgeting a| Enables CPU budgeting options for the Tier 2 compiler. |false

|-XX:CIMaxCompilerThreads=<number of threads> a|Defines the maximum number of threads which can be dedicated to the compiler. This is overridden by -XX:CompilerTier2BudgetingCPUPercent and -XX:CompilerTier2BudgetingWarmupCPUPercent |Dependent on the CPU count

|-XX:CIMaxCompilerThreadsPercent=<percent of threads> a|Defines the maximum number of threads, as a percent, which can be dedicated to the compiler. The number of threads is rounded up to the nearest whole number. If you want to use a fractional number, use the option -XX:CompilerTier2BudgetingCPUPercent instead. -XX:CompilerTier2BudgetingCPUPercent overrides this flag. |Dependent on the CPU count

|-XX:CompilerWarmupExtraThreads=<number of threads> a|Defines how many extra threads over -XX:CIMaxCompilerThreads the Tier 2 compiler can use during warmup, during the duration specified by -XX:CompilerWarmupPeriodSeconds. After warmup, the value of -XX:CIMaxCompilerThreads shall be respected. |0

|-XX:ProfilePreMainTier2ExtraCompilerThreads=<number of threads> a|Defines how many extra threads over -XX:CIMaxCompilerThreads the Tier 2 compiler can use during warmup, before Main class is compiled. |0

|-XX:CompilerWarmupPeriodSeconds=<value in seconds> a|Defines how long the Tier 2 compiler warmup period shall be, in seconds. |0

|-XX:CompilerTier2BudgetingWarmupCPUPercent=<value> a|Specifies the CPU Percent which can be used for Tier 2 compilation during warmup, i.e. during the duration set with -XX:CompilerWarmupPeriodSeconds. The resulting value can be less than 1 or any other non-whole number. The Tier 2 compiler waits for this percent of CPU cores to be available before continuing. To use this option, you must have -XX:+EnableTier2CompilerBudgeting set to true. Note that 100 percent CPU usage is the limit of CPU cores available to the JVM environment, which can be defined by container limits and other factors outside of the JVM process. |0

|-XX:CompilerTier2BudgetingCPUPercent=<value> a|Specifies the CPU percent which can be used for Tier 2 compilation post warmup, i.e. after the duration set with -XX:CompilerWarmupPeriodSeconds. The resulting value can be less than 1 or any other non-whole number. To use this option, you must have -XX:+EnableTier2CompilerBudgeting set to true. Note that 100 percent CPU usage is the limit of CPU cores available to the JVM environment, which can be defined by container limits and other factors outside of the JVM process. |67

|-XX:CompilerTier2BudgetWindowDurationMs=<value in ms> a|Specifies a window of time, in ms, in which the average CPU consumption of the compiler shall not exceed -XX:CompilerTier2BudgetingCPUPercent. To use this option, you must have -XX:+EnableTier2CompilerBudgeting set to true. |1000

|Command Line Option |Description |Default

|-XX:TopTierCompileThresholdTriggerMillis=<value in ms> a|Previously TopTierCompileThresholdMs - Controls the triggering time limit (in ms) in which the method needs to reach the compile threshold in order to be queued for compilation. If the threshold is reached, but not within this time limit, the method is ignored and the timer starts over again.

This option assigns the same value to TopTierHotCompileThresholdTriggerMillis and TopTierWarmCompileThresholdTriggerMillis, creating a boundary between hot and cold ranks while eliminating the warm rank.

This option must not be set if you are using TopTierHotCompileThresholdTriggerMillis and TopTierWarmCompileThresholdTriggerMillis to specify hot, warm, and cold ranks. |600000

|-XX:TopTierHotCompileThresholdTriggerMillis=<value in ms> a|Sets an upper bound for min-time-between-promotions for the hot rank and a lower bound for the warm rank. The upper bound for the hot rank is 1ms less than the value set. |60000

|-XX:TopTierWarmCompileThresholdTriggerMillis=<value in ms> a|Sets the upper bound for min-time-between-promotions for the warm rank and lower bound for the cold rank. The upper bound for the warm rank is 1ms less than the value set. |600000

|-XX:TopTierWarmCompileCpuPercent a|Specifies the percentage of CPU time from the total budget available to compiler threads that can be spent on warm rank compilation. hot ranks are given 100% and cold ranks are given 0%. |25

|Command Line Option |Description |Default

|-XX:ProfileLogOut=<filename> a|ProfileLogOut enables Zing to record compilations from the current run. <filename> is the name of the profile that the JVM reads as input to ReadyNow. If prefixed with cnc://, it will attempt to pull the profile from Cloud Native Compiler.

If ReadyNow is configured as a rolling profile (with ProfileLogIn equal to ProfileLogOut), The JVM creates a backup of the input profile at startup before the profile is being read into memory. Otherwise, the file will be overwritten. |null

|-XX:ProfileLogIn=<filename> a|ProfileLogIn allows Zing to base its decisions on the information from a previous run. The current ProfileLogIn file information will be read in its entirety - before Zing starts to create a new ProfileLogOut log. <filename> is the name of the profile that the JVM reads as input to ReadyNow. If prefixed with cnc://, it will attempt to pull the profile from Cloud Native Compiler. |null

|-XX:ProfileLogName=<name> a|Name of the profile that the JVM both reads from and writes to. If prefixed with cnc://, it will attempt to write from Cloud Native Compiler.

Replaces ProfileLogIn and ProfileLogOut. Can be used in place of -XX:ProfileLogIn=<profile1> -XX:ProfileLogOut=<profile1> |null

|-XX:ProfileLogDumpInputToFile=<name> a|Dump input profile to the specified path. For debugging purposes only. |null

|-XX:ProfileLogDumpOutputToFile=<name> a| Dump output profile to the specified path. For debugging purposes only. |null

|-XX:ProfileLogMaxSize=<value>[K\|M\|G] a|Specifies the maximum size that a ReadyNow profile log is allowed to reach. Units can be specified in kilobytes (K or k), megabytes (M or m), or gigabytes (G or g). Profiles will be truncated at this size, regardless of whether the application has actually been completely warmed up. It is recommended to either not set this size explicitly, or set it generously if required, for example:

-XX:ProfileLogMaxSize=1G

0 = unlimited |0

|-XX:ProfileLogOutMaxNominatedGenerationCount=<value> a|When used with Cloud Native Compiler, specifies the maximum generation of a profile that a VM will nominate. If ContinueRecordingAfterPromotion (CNC server-side parameter) is set to false (default), then the JVM will not output another generation after this limit has been reached. If ContinueRecordingAfterPromotion is true, the JVM will output another generation to Cloud Native Compiler but will never nominate it. These additional generations are for debugging and analysis only.

0 = unlimited |0

|-XX:ProfileLogOutNominationMinTimeSec=<value in seconds> a|When used with Cloud Native Compiler, the minimum time, in seconds, a profile must record before CNC will nominate it as a candidate. If no -XX:ProfileLogOutNominationMinTimeSec is set, then the candidate is nominated by CNC when -XX:ProfileLogTimeLimitSeconds is reached.

0 = any duration eligible, -1 means it will never be promoted |120

|-XX:ProfileLogTimeLimitSeconds=<value in seconds> a|Instructs ReadyNow to stop adding to the profile log after a period of N seconds regardless of where the application has been completely warmed up. It is recommended to either not set this size explicitly, or set it generously if required.

0 = unlimited |0

|-XX:ProfileLogServiceConnectionTimeoutMillis=<value in ms> a| Timeout on establishing remote connection and timeout on interval between downloading two chunks. Specified in milliseconds. |5000

|-XX:ProfileLogOutNominationMinSize=<value in bytes> a|Indicate to server that the produced profile is eligible for promotion after specified amount of bytes recorded.

0 = any size eligible, -1 means it will never be promoted |1m

|-XX:[+/-]ProfileLogOutVerbose a|Enables logging of verbose, optional tracing information in -XX:ProfileLogOut |true

|-XX:ProfilePersistCodeProfilesPeriodSec=<value in seconds> a|Enables periodic dumping of runtime bytecode profiling counters to the ReadyNow profile log at the interval specified, in addition to the regular on-demand ReadyNow profile log writes. If you set the option to 0, a dump of the additional information occurs only on a graceful JVM shutdown. |-1, disabled

|Command Line Option |Description |Default

|-XX:[+/-]FalconUseCompileStashing a|Enables/disables Compile Stashing, populates the cache. |false. Before 19.12.0.0, true if -XX:ProfileLogOut is set.

|-XX:FalconObjectCacheRoot=<path> a|Sets the cache location. By default, different instances of Zing running on the same host share the same stash location. However, different instances can be configured to use different locations via the FalconObjectCacheRoot option. |$HOME/.zing/falcon-cache/<zvm_version>/

|-XX:[+/-]FalconLoadObjectCache a|Enables loading from compile cache. |false

|-XX:[+/-]FalconSaveObjectCache a|Enables saving to compile cache. |false

|-XX:FalconMaxStashedCompileSize=<max_size in bytes> a|Specifies the maximum size of a stashed compile entry. When running multiple virtual machines concurrently, different cache sizes for different virtual machines are not recommended. Similar cache sizes are advised. |0

|-XX:FalconMaxCacheSize=<max_size in bytes> a|Specifies the maximum size of the compile cache. |10 GB

|-XX:[+/-]FalconObjectCachePrintReport a|Prints stashing statistics. |false

|-XX:[+/-]FalconObjectCachePrintPrecompilationReport a|Prints stashing report at the end of ReadyNow precompilation. |false

|Command Line Option |Description |Default

|-XX:[+/-]UseTickProfiler a|Enables and disables profiling of processor core time spent between various software execution units (for example, threads, methods, and run-time tasks).

Due to known issues with version 3.10 and earlier Linux kernels, including those used in RHEL 7.x and CentOS 7.x, using +UseTickProfiler in production should be done with caution, as potential hangs may result under heavy loads. |false

|Command Line Option |Description |Default

|-XX:[+/-]ExitOnOutOfMemoryError a|Enables the JVM exit on the first occurrence of an out-of-memory error. Useful if you prefer restarting an instance of the JVM to handling out of memory errors. |false

|-XX:[+/-]CrashOnOutOfMemoryError a|Enables the JVM crash and produce text and binary crash files when an out-of-memory error occurs. |false

|Command Line Option |Description |Default

|-XX:[+/-]FlightRecorder a|The Java Flight Recorder (JFR) is always available in Zing, this flag is not needed to use JFR.

This flag is useful only to prevent JFR from being activated by users or from within an application. That can be achieved by adding -XX:-FlightRecorder to the command line. It gives no performance benefit.

See Using Java Flight Recorder for details. |false

JFR remains available until -XX:-FlightRecorder is set

|-XX:StartFlightRecording a|Starts a flight recording from the command line with recording parameters provided as a value for this option.

For example, -XX:StartFlightRecording=filename=myrecording.jfr starts a recording in the file system while -XX:StartFlightRecording=disk=false,filename=myrecording.jfr starts an in-memory recording. In both cases the result is written to the myrecording.jfr file at the end of the JVM session. For the description of additional Java Flight Recording (JFR) parameters refer to JFR resources available in the Internet. |null

|-XX:FlightRecorderOptions a|Specifies additional parameters to configure Java Flight Recorder (JFR). For the description of additional JFR parameters refer to JFR resources available in the Internet. |null

|-XX:JFRDescribeLiveSetPercentage=<value> a|Specifies the percentage amount of a live set to be described by recorded JFR events. To omit some minor events from the recording, change the value of this option to a smaller number, e.g., 90. |99

|-XX:[+/-]UseTickProfilerAsJFRThreadSampler a|Enables Zing to use the Tick Profiler instead of the JFR Thread Sampler. When set to true, EventExecutionSample JFR events are generated from data provided by the Tick Profiler. |true

|-XX:TickProfilerNotifierIntervalMillis=<value in ms> a|Controls the interval between consecutive polls for the new Tick Profiler samples to pass them to the JFR in-memory buffer. This option has an effect only when -XX:+UseTickProfilerAsJFRThreadSampler is specified. |200

|Command-Line Option |Description | Default

|-XX:[+/-]ReportUsedAsCommitted a|The MemoryMXBean.getHeapMemoryUsage() method of MXBeans API returns the value of the Committed memory equal to the amount of JVM heap memory guaranteed as available for running an application (see Understanding Heap Memory Management for details). To switch to the old behavior of the MXBeans interface that returned the value of the Committed memory equal to Used memory, change the value of this option to true. |false

|-XX:[+/-]MimicG1GCMemoryManagerNames a|Changes garbage collector names returned by GarbageCollectorMXBean from GPGC to G1. To define exact New and Old GC names use -XX:GPGCNewGCMemoryManagerName="GPGC New" and -XX:GPGCOldGCMemoryManagerName="GPGC Old" respectively. This option provides a workaround for applications that do not recognize GPGC names such as Logstash. |false

|-XX:GPGCNewGCMemoryManagerName=<New collector name> a|Sets the name returned by GarbageCollectorMXBean for the New generation collector. |GPGC New

|-XX:GPGCOldGCMemoryManagerName=<Old collector name> a|Sets the name returned by GarbageCollectorMXBean for the Old generation collector. |GPGC Old

|-XX:[+/-]IncludeNonObjectHeapInReportedJavaHeap a|Makes Java heap reporting APIs and Tools include "non-object" use. |false

|-XX:[+/-]ReportConstantMaxPossibleHeapAsMaxJavaHeap a|Lets APIs which report max heap capacity be aware of elasticity. |false