v8
V8 is Google’s open source high-performance JavaScript and WebAssembly engine, written in C++.
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v8::ResourceConstraints Class Reference

#include <v8-isolate.h>

Collaboration diagram for v8::ResourceConstraints:

Public Member Functions

void ConfigureDefaultsFromHeapSize (size_t initial_heap_size_in_bytes, size_t maximum_heap_size_in_bytes)
 
void ConfigureDefaults (uint64_t physical_memory, uint64_t virtual_memory_limit)
 
uint32_t * stack_limit () const
 
void set_stack_limit (uint32_t *value)
 
size_t code_range_size_in_bytes () const
 
void set_code_range_size_in_bytes (size_t limit)
 
size_t max_old_generation_size_in_bytes () const
 
void set_max_old_generation_size_in_bytes (size_t limit)
 
size_t max_young_generation_size_in_bytes () const
 
void set_max_young_generation_size_in_bytes (size_t limit)
 
size_t initial_old_generation_size_in_bytes () const
 
void set_initial_old_generation_size_in_bytes (size_t initial_size)
 
size_t initial_young_generation_size_in_bytes () const
 
void set_initial_young_generation_size_in_bytes (size_t initial_size)
 

Private Attributes

size_t code_range_size_ = 0
 
size_t max_old_generation_size_ = 0
 
size_t max_young_generation_size_ = 0
 
size_t initial_old_generation_size_ = 0
 
size_t initial_young_generation_size_ = 0
 
uint32_t * stack_limit_ = nullptr
 

Static Private Attributes

static constexpr size_t kMB = 1048576u
 

Detailed Description

A set of constraints that specifies the limits of the runtime's memory use. You must set the heap size before initializing the VM - the size cannot be adjusted after the VM is initialized.

If you are using threads then you should hold the V8::Locker lock while setting the stack limit and you must set a non-default stack limit separately for each thread.

The arguments for set_max_semi_space_size, set_max_old_space_size, set_max_executable_size, set_code_range_size specify limits in MB.

The argument for set_max_semi_space_size_in_kb is in KB.

Definition at line 64 of file v8-isolate.h.

Member Function Documentation

◆ code_range_size_in_bytes()

size_t v8::ResourceConstraints::code_range_size_in_bytes ( ) const
inline

The amount of virtual memory reserved for generated code. This is relevant for 64-bit architectures that rely on code range for calls in code.

When V8_COMPRESS_POINTERS_IN_SHARED_CAGE is defined, there is a shared process-wide code range that is lazily initialized. This value is used to configure that shared code range when the first Isolate is created. Subsequent Isolates ignore this value.

Definition at line 114 of file v8-isolate.h.

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◆ ConfigureDefaults()

void v8::ResourceConstraints::ConfigureDefaults ( uint64_t physical_memory,
uint64_t virtual_memory_limit )

Configures the constraints with reasonable default values based on the capabilities of the current device the VM is running on.

Parameters
physical_memoryThe total amount of physical memory on the current device, in bytes.
virtual_memory_limitThe amount of virtual memory on the current device, in bytes, or zero, if there is no limit.

Definition at line 529 of file api.cc.

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◆ ConfigureDefaultsFromHeapSize()

void v8::ResourceConstraints::ConfigureDefaultsFromHeapSize ( size_t initial_heap_size_in_bytes,
size_t maximum_heap_size_in_bytes )

Configures the constraints with reasonable default values based on the provided heap size limit. The heap size includes both the young and the old generation.

Parameters
initial_heap_size_in_bytesThe initial heap size or zero. By default V8 starts with a small heap and dynamically grows it to match the set of live objects. This may lead to ineffective garbage collections at startup if the live set is large. Setting the initial heap size avoids such garbage collections. Note that this does not affect young generation garbage collections.
maximum_heap_size_in_bytesThe hard limit for the heap size. When the heap size approaches this limit, V8 will perform series of garbage collections and invoke the NearHeapLimitCallback. If the garbage collections do not help and the callback does not increase the limit, then V8 will crash with V8::FatalProcessOutOfMemory.

Definition at line 503 of file api.cc.

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◆ initial_old_generation_size_in_bytes()

size_t v8::ResourceConstraints::initial_old_generation_size_in_bytes ( ) const
inline

Definition at line 143 of file v8-isolate.h.

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◆ initial_young_generation_size_in_bytes()

size_t v8::ResourceConstraints::initial_young_generation_size_in_bytes ( ) const
inline

Definition at line 150 of file v8-isolate.h.

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◆ max_old_generation_size_in_bytes()

size_t v8::ResourceConstraints::max_old_generation_size_in_bytes ( ) const
inline

The maximum size of the old generation. When the old generation approaches this limit, V8 will perform series of garbage collections and invoke the NearHeapLimitCallback. If the garbage collections do not help and the callback does not increase the limit, then V8 will crash with V8::FatalProcessOutOfMemory.

Definition at line 124 of file v8-isolate.h.

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◆ max_young_generation_size_in_bytes()

size_t v8::ResourceConstraints::max_young_generation_size_in_bytes ( ) const
inline

The maximum size of the young generation, which consists of two semi-spaces and a large object space. This affects frequency of Scavenge garbage collections and should be typically much smaller that the old generation.

Definition at line 136 of file v8-isolate.h.

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◆ set_code_range_size_in_bytes()

void v8::ResourceConstraints::set_code_range_size_in_bytes ( size_t limit)
inline

Definition at line 115 of file v8-isolate.h.

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◆ set_initial_old_generation_size_in_bytes()

void v8::ResourceConstraints::set_initial_old_generation_size_in_bytes ( size_t initial_size)
inline

Definition at line 146 of file v8-isolate.h.

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◆ set_initial_young_generation_size_in_bytes()

void v8::ResourceConstraints::set_initial_young_generation_size_in_bytes ( size_t initial_size)
inline

Definition at line 153 of file v8-isolate.h.

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◆ set_max_old_generation_size_in_bytes()

void v8::ResourceConstraints::set_max_old_generation_size_in_bytes ( size_t limit)
inline

Definition at line 127 of file v8-isolate.h.

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◆ set_max_young_generation_size_in_bytes()

void v8::ResourceConstraints::set_max_young_generation_size_in_bytes ( size_t limit)
inline

Definition at line 139 of file v8-isolate.h.

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◆ set_stack_limit()

void v8::ResourceConstraints::set_stack_limit ( uint32_t * value)
inline

Definition at line 103 of file v8-isolate.h.

◆ stack_limit()

uint32_t * v8::ResourceConstraints::stack_limit ( ) const
inline

The address beyond which the VM's stack may not grow.

Definition at line 102 of file v8-isolate.h.

Member Data Documentation

◆ code_range_size_

size_t v8::ResourceConstraints::code_range_size_ = 0
private

Definition at line 159 of file v8-isolate.h.

◆ initial_old_generation_size_

size_t v8::ResourceConstraints::initial_old_generation_size_ = 0
private

Definition at line 162 of file v8-isolate.h.

◆ initial_young_generation_size_

size_t v8::ResourceConstraints::initial_young_generation_size_ = 0
private

Definition at line 163 of file v8-isolate.h.

◆ kMB

size_t v8::ResourceConstraints::kMB = 1048576u
staticconstexprprivate

Definition at line 158 of file v8-isolate.h.

◆ max_old_generation_size_

size_t v8::ResourceConstraints::max_old_generation_size_ = 0
private

Definition at line 160 of file v8-isolate.h.

◆ max_young_generation_size_

size_t v8::ResourceConstraints::max_young_generation_size_ = 0
private

Definition at line 161 of file v8-isolate.h.

◆ stack_limit_

uint32_t* v8::ResourceConstraints::stack_limit_ = nullptr
private

Definition at line 164 of file v8-isolate.h.


The documentation for this class was generated from the following files: