diff --git a/.github/workflows/MemLayoutGen.yaml b/.github/workflows/MemLayoutGen.yaml
new file mode 100644
index 00000000..c233d8f5
--- /dev/null
+++ b/.github/workflows/MemLayoutGen.yaml
@@ -0,0 +1,42 @@
+name: MemLayout Info Generating
+on:
+  pull_request:
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    continue-on-error: true
+    strategy:
+      matrix:
+        version:
+          - '1.3.1'
+          - '1.4.2'
+          - '1.5.3'
+          - '1.5.4'
+          - '1.6.1'
+        os:
+          - ubuntu-latest
+          - windows-latest
+          - macOS-latest
+        arch:
+          - x64
+          - x86
+        exclude:
+          - os: macOS-latest
+            arch: x86
+    steps:
+      - name: Set up MinGW
+        uses: egor-tensin/setup-mingw@v2
+        with:
+          platform: i686
+          cc: 1
+        if: ${{ matrix.os == 'windows-latest' && matrix.arch == 'x86' }}
+      - uses: actions/checkout@v2
+      - uses: julia-actions/setup-julia@v1
+        with:
+          version: ${{ matrix.version }}
+          arch: ${{ matrix.arch }}
+      - run: julia .github/workflows/tasklayout/memlayout.jl
+      - uses: EndBug/add-and-commit@v7
+        with:
+          add: 'src/memlayout'
+          author_name: GitHub Actions
diff --git a/.github/workflows/Testing.yaml b/.github/workflows/Testing.yaml
index 8d6d66e7..fa17a364 100644
--- a/.github/workflows/Testing.yaml
+++ b/.github/workflows/Testing.yaml
@@ -7,7 +7,7 @@ on:
 jobs:
   test:
     runs-on: ${{ matrix.os }}
-    continue-on-error: ${{ matrix.version == 'nightly' }}
+    continue-on-error: true # ${{ matrix.version == 'nightly' }}
     strategy:
       matrix:
         version:
diff --git a/.github/workflows/tasklayout/memlayout.cpp b/.github/workflows/tasklayout/memlayout.cpp
new file mode 100644
index 00000000..6004eb9e
--- /dev/null
+++ b/.github/workflows/tasklayout/memlayout.cpp
@@ -0,0 +1,138 @@
+/**
+ * linux64: g++ -I $JULIA_HOME/include/julia/ memlayout.cpp -o memlayout
+ * linux32: apt-get install g++-multilib
+ *          g++ -march=pentium4 -m32 -I $JULIA_HOME/include/julia/ memlayout.cpp -o memlayout
+ * macOS:   g++ -std=c++11 -I $JULIA_APP/Contents/Resources/julia/include/julia/ memlayout.cpp -o memlayout
+ * win64:   g++ -I $JULIA_HOME/include/julia/ memlayout.cpp -o memlayout
+ * win32:   g++ -I $JULIA_HOME/include/julia/ memlayout.cpp -o memlayout
+ **/
+
+#include <string>
+#include <map>
+#include <fstream>
+#include <sstream>
+
+#include <cstddef>
+
+#include "julia.h"
+
+std::string jl_ver(std::string sep=".") {
+    std::ostringstream oss;
+    oss << JULIA_VERSION_MAJOR << sep
+        << JULIA_VERSION_MINOR << sep
+        << JULIA_VERSION_PATCH;
+    return oss.str();
+}
+
+std::string platform() {
+#ifdef _WIN32
+#ifdef _WIN64
+    return "windows-x86_64";
+#endif
+    return "windows-x86";
+#endif
+#ifdef __APPLE__
+    return "darwin-x86_64";
+#endif
+#ifdef __linux__
+#ifdef __x86_64
+    return "linux-x86_64";
+#else
+    return "linux-x86";
+#endif
+#endif
+}
+
+std::map<std::string, size_t> task_field_offsets() {
+    std::map<std::string, size_t> data;
+
+#define field_info(f) data[#f] = offsetof(jl_task_t, f)
+
+    field_info(next);         // 131 142 153 154 160 170
+    field_info(queue);        // 131 142 153 154 160 170
+    field_info(tls);          // 131 142 153 154 160 170
+    field_info(donenotify);   // 131 142 153 154 160 170
+    field_info(result);       // 131 142 153 154 160 170
+
+#if JULIA_VERSION_MAJOR == 1 && JULIA_VERSION_MINOR < 6
+    field_info(state);        // 131 142 153 154
+    field_info(exception);    // 131 142 153 154
+    field_info(backtrace);    // 131 142 153 154
+#endif
+
+    field_info(logstate);     // 131 142 153 154 160 170
+    field_info(start);        // 131 142 153 154 160 170
+    field_info(sticky);       // 131 142 153 154 160 170
+
+#if JULIA_VERSION_MAJOR == 1 && JULIA_VERSION_MINOR > 5
+    field_info(_state);       //                 160 170
+    field_info(_isexception); //                 160 170
+#endif
+
+#if JULIA_VERSION_MAJOR == 1 && JULIA_VERSION_MINOR > 6
+    field_info(rngState0);    //                     170
+    field_info(rngState1);    //                     170
+    field_info(rngState2);    //                     170
+    field_info(rngState3);    //                     170
+#endif
+
+    // hidden state
+    field_info(gcstack);      // 131 142 153 154 160 170
+
+#if JULIA_VERSION_MAJOR == 1 &&                                 \
+    (JULIA_VERSION_MINOR > 6 || JULIA_VERSION_MINOR < 5 ||      \
+        (JULIA_VERSION_MINOR == 5 && JULIA_VERSION_PATCH < 4))
+    field_info(world_age);    // 131 142 153         170
+#endif
+
+#if JULIA_VERSION_MAJOR == 1 && JULIA_VERSION_MINOR > 6
+    field_info(ptls);         //                     170
+#endif
+    field_info(tid);          // 131 142 153 154 160 170
+    field_info(prio);         // 131 142 153 154 160 170
+    field_info(excstack);     // 131 142 153 154 160 170
+    field_info(eh);           // 131 142 153 154 160 170
+    field_info(ctx);          // 131 142 153 154 160 170
+
+#if JULIA_VERSION_MAJOR == 1 && JULIA_VERSION_MINOR < 6
+    field_info(locks);        // 131 142 153 154
+    field_info(timing_stack); // 131 142 153 154
+#endif
+    // field_info(copy_stack_ctx);
+
+#if defined(JL_TSAN_ENABLED)
+    field_info(tsan_state);   //                     170
+#endif
+
+    field_info(stkbuf);       // 131 142 153 154 160 170
+    field_info(bufsz);        // 131 142 153 154 160 170
+    // field_info(copy_stack);
+    // field_info(started);
+
+#undef field_info
+    data["copy_stack"] = offsetof(jl_task_t, bufsz) + sizeof(size_t);
+    data["sizeof_ctx"] = sizeof(((jl_task_t*)0)->ctx);
+    // data["sizeof_stack_ctx"] = sizeof(((jl_task_t*)0)->copy_stack_ctx);
+    data["tls_base_context"] = offsetof(struct _jl_tls_states_t, base_ctx);
+    // data["tls_copy_stack_ctx"] = offsetof(struct _jl_tls_states_t, copy_stack_ctx);
+    return data;
+}
+
+int main() {
+    std::ofstream ofs(platform() +"-v" + jl_ver("_") + ".jl", std::ofstream::out);
+
+    ofs << "ALL_TASK_OFFSETS[("
+        << '"' << platform() << '"' << ", "
+        << "v\"" << jl_ver() <<"\""
+        <<")] = Dict(\n";
+    ofs << "    :END => " << sizeof(jl_task_t) << ",\n";
+
+    std::map<std::string, size_t> data = task_field_offsets();
+    for(auto kv: data) {
+        ofs << "    :" << kv.first << " => " << kv.second << ",\n";
+    }
+    ofs << ")\n";
+
+    ofs.close();
+    return 0;
+}
diff --git a/.github/workflows/tasklayout/memlayout.jl b/.github/workflows/tasklayout/memlayout.jl
new file mode 100644
index 00000000..78ec9ae5
--- /dev/null
+++ b/.github/workflows/tasklayout/memlayout.jl
@@ -0,0 +1,32 @@
+const ARCH = @static if string(Sys.ARCH)[1] == 'i'
+    "x86"
+else
+    string(Sys.ARCH)
+end
+
+const PLATFORM = @static if Sys.islinux()
+    "linux-" * ARCH
+elseif Sys.iswindows()
+    "windows-" * ARCH
+elseif Sys.isapple()
+    "darwin-" * ARCH
+end
+
+OUTPUT = "$(PLATFORM)-v$(VERSION.major)_$(VERSION.minor)_$(VERSION.patch).jl"
+OUTPUT_DEST = joinpath("src/memlayout", OUTPUT)
+
+isfile(OUTPUT_DEST) && exit(0)
+
+const PROJECT_DIR = (@__DIR__) |> dirname |> dirname |> dirname
+const INCLUDE = joinpath(dirname(Sys.BINDIR), "include/julia")
+const OPTIONS = if string(Sys.ARCH)[1] == 'i'
+    Sys.islinux() && run(`sudo apt-get install g++-multilib -y`)
+    ["-std=c++11","-march=pentium4", "-m32", "-static-libgcc", "-static-libstdc++"]
+else
+    ["-std=c++11"]
+end
+
+run(`g++ $(OPTIONS) -I$(INCLUDE) $(PROJECT_DIR)/.github/workflows/tasklayout/memlayout.cpp -o memlayout-gen.exe`)
+run(`./memlayout-gen.exe`)
+
+isfile(OUTPUT) && Base.Filesystem.mv(OUTPUT, OUTPUT_DEST)
diff --git a/Project.toml b/Project.toml
index 75bccfc5..9ee5aa26 100644
--- a/Project.toml
+++ b/Project.toml
@@ -6,17 +6,18 @@ repo = "https://github.com/TuringLang/Libtask.jl.git"
 version = "0.5.3"
 
 [deps]
+Libdl = "8f399da3-3557-5675-b5ff-fb832c97cbdb"
 Libtask_jll = "3ae2931a-708c-5973-9c38-ccf7496fb450"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
 [compat]
-Libtask_jll = "0.4"
+Libtask_jll = "0.5.1"
 julia = "1.3"
 
 [extras]
-Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 BenchmarkTools = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
 test = ["Test", "BenchmarkTools"]
diff --git a/src/Libtask.jl b/src/Libtask.jl
index e647e65d..22897916 100644
--- a/src/Libtask.jl
+++ b/src/Libtask.jl
@@ -1,9 +1,19 @@
 module Libtask
 
+using Libdl
 using Libtask_jll
 
 export CTask, consume, produce, TArray, tzeros, tfill, TRef
 
+function __init__()
+    @static if VERSION < v"1.6.0"
+        push!(Libdl.DL_LOAD_PATH,
+              Libtask_jll.get_libtask_julia_path() |> dirname)
+        Libdl.dlopen(Libtask_jll.libtask_julia_path)
+    end
+end
+
+include("memlayout/main.jl")
 include("ctask.jl")
 include("tarray.jl")
 include("tref.jl")
diff --git a/src/ctask.jl b/src/ctask.jl
index 8665c7b5..a3e6a754 100644
--- a/src/ctask.jl
+++ b/src/ctask.jl
@@ -49,7 +49,18 @@ function enable_stack_copying(t::Task)
     if istaskfailed(t)
         error("only runnable or finished tasks' stack can be copied.")
     end
-    return ccall((:jl_enable_stack_copying, libtask_julia), Any, (Any,), t)::Task
+    # return ccall((:jl_enable_stack_copying, libtask_julia),
+    #             Any, (Any,), t)::Task
+    copy_stack = internal_getfield(t, :copy_stack, Int32)
+    if copy_stack == 0
+        internal_setfield(t, :copy_stack, Int32(1))
+        internal_setfield(t, :bufsz, Csize_t(0))
+        ccall((:jl_reset_task_ctx, libtask_julia),
+              Cvoid, (Any, Csize_t, Csize_t, Csize_t),
+              t, TASK_OFFSETS[:ctx], TASK_OFFSETS[:sizeof_ctx],
+              TASK_OFFSETS[:tls_base_context])
+    end
+    return t
 end
 
 """
@@ -101,7 +112,30 @@ function Base.copy(ctask::CTask)
         error("only runnable or finished tasks can be copied.")
     end
 
-    newtask = ccall((:jl_clone_task, libtask_julia), Any, (Any,), task)::Task
+    # memory copy
+    # newtask = ccall((:jl_clone_task, libtask_julia), Any, (Any,), task)::Task
+    newtask = ccall((:jl_clone_task_opaque, libtask_julia),
+                    Any, (Any, Csize_t), task, TASK_OFFSETS[:END])::Task
+    internal_setfield(newtask, :exception, nothing)
+    internal_setfield(newtask, :backtrace, nothing)
+    internal_setfield(newtask, :tls, nothing)
+    internal_setfield(newtask, :result, nothing)
+    internal_setfield(newtask, :donenotify, nothing)
+    internal_setfield(newtask, :excstack, C_NULL)
+    internal_setfield(newtask, :ptls, C_NULL)
+    internal_setfield(newtask, :gcstack, C_NULL)
+
+    if haskey(TASK_OFFSETS, :stkbuf) && haskey(TASK_OFFSETS, :bufsz)
+        old_stkbuf = internal_getfield(task, :stkbuf, Ptr)
+        if old_stkbuf != C_NULL
+            internal_setfield(task, :bufsz, Csize_t(0))
+        else
+            internal_setfield(newtask, :stkbuf, C_NULL)
+        end
+        internal_setfield(newtask, :bufsz, Csize_t(0))
+    end
+    memset(newtask, 0, :locks)
+    # memory copy done
 
     task.storage[:n_copies] = 1 + n_copies(task)
     newtask.storage = copy(task.storage)
diff --git a/src/memlayout/darwin-x86_64-v1_3_1.jl b/src/memlayout/darwin-x86_64-v1_3_1.jl
new file mode 100644
index 00000000..f154b529
--- /dev/null
+++ b/src/memlayout/darwin-x86_64-v1_3_1.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("darwin-x86_64", v"1.3.1")] = Dict(
+    :END => 568,
+    :backtrace => 56,
+    :bufsz => 248,
+    :copy_stack => 256,
+    :ctx => 84,
+    :donenotify => 32,
+    :eh => 264,
+    :exception => 48,
+    :excstack => 280,
+    :gcstack => 272,
+    :locks => 304,
+    :logstate => 64,
+    :next => 0,
+    :prio => 298,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 152,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 240,
+    :tid => 296,
+    :timing_stack => 560,
+    :tls => 16,
+    :tls_base_context => 6664,
+    :world_age => 288,
+)
diff --git a/src/memlayout/darwin-x86_64-v1_4_2.jl b/src/memlayout/darwin-x86_64-v1_4_2.jl
new file mode 100644
index 00000000..82c858ed
--- /dev/null
+++ b/src/memlayout/darwin-x86_64-v1_4_2.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("darwin-x86_64", v"1.4.2")] = Dict(
+    :END => 568,
+    :backtrace => 56,
+    :bufsz => 248,
+    :copy_stack => 256,
+    :ctx => 84,
+    :donenotify => 32,
+    :eh => 264,
+    :exception => 48,
+    :excstack => 280,
+    :gcstack => 272,
+    :locks => 304,
+    :logstate => 64,
+    :next => 0,
+    :prio => 298,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 152,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 240,
+    :tid => 296,
+    :timing_stack => 560,
+    :tls => 16,
+    :tls_base_context => 6664,
+    :world_age => 288,
+)
diff --git a/src/memlayout/darwin-x86_64-v1_5_3.jl b/src/memlayout/darwin-x86_64-v1_5_3.jl
new file mode 100644
index 00000000..6d5bc272
--- /dev/null
+++ b/src/memlayout/darwin-x86_64-v1_5_3.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("darwin-x86_64", v"1.5.3")] = Dict(
+    :END => 568,
+    :backtrace => 56,
+    :bufsz => 248,
+    :copy_stack => 256,
+    :ctx => 84,
+    :donenotify => 32,
+    :eh => 264,
+    :exception => 48,
+    :excstack => 280,
+    :gcstack => 272,
+    :locks => 304,
+    :logstate => 64,
+    :next => 0,
+    :prio => 298,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 152,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 240,
+    :tid => 296,
+    :timing_stack => 560,
+    :tls => 16,
+    :tls_base_context => 6672,
+    :world_age => 288,
+)
diff --git a/src/memlayout/darwin-x86_64-v1_5_4.jl b/src/memlayout/darwin-x86_64-v1_5_4.jl
new file mode 100644
index 00000000..ec6ddd4e
--- /dev/null
+++ b/src/memlayout/darwin-x86_64-v1_5_4.jl
@@ -0,0 +1,27 @@
+ALL_TASK_OFFSETS[("darwin-x86_64", v"1.5.4")] = Dict(
+    :END => 560,
+    :backtrace => 56,
+    :bufsz => 248,
+    :copy_stack => 256,
+    :ctx => 84,
+    :donenotify => 32,
+    :eh => 264,
+    :exception => 48,
+    :excstack => 280,
+    :gcstack => 272,
+    :locks => 296,
+    :logstate => 64,
+    :next => 0,
+    :prio => 290,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 152,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 240,
+    :tid => 288,
+    :timing_stack => 552,
+    :tls => 16,
+    :tls_base_context => 6672,
+)
diff --git a/src/memlayout/darwin-x86_64-v1_6_1.jl b/src/memlayout/darwin-x86_64-v1_6_1.jl
new file mode 100644
index 00000000..cc4892eb
--- /dev/null
+++ b/src/memlayout/darwin-x86_64-v1_6_1.jl
@@ -0,0 +1,24 @@
+ALL_TASK_OFFSETS[("darwin-x86_64", v"1.6.1")] = Dict(
+    :END => 264,
+    :_isexception => 58,
+    :_state => 56,
+    :bufsz => 240,
+    :copy_stack => 248,
+    :ctx => 80,
+    :donenotify => 24,
+    :eh => 72,
+    :excstack => 64,
+    :gcstack => 256,
+    :logstate => 40,
+    :next => 0,
+    :prio => 62,
+    :queue => 8,
+    :result => 32,
+    :sizeof_ctx => 152,
+    :start => 48,
+    :sticky => 57,
+    :stkbuf => 232,
+    :tid => 60,
+    :tls => 16,
+    :tls_base_context => 6680,
+)
diff --git a/src/memlayout/linux-x86-v1_3_1.jl b/src/memlayout/linux-x86-v1_3_1.jl
new file mode 100644
index 00000000..66461532
--- /dev/null
+++ b/src/memlayout/linux-x86-v1_3_1.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("linux-x86", v"1.3.1")] = Dict(
+    :END => 364,
+    :backtrace => 28,
+    :bufsz => 204,
+    :copy_stack => 208,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 212,
+    :exception => 24,
+    :excstack => 220,
+    :gcstack => 216,
+    :locks => 232,
+    :logstate => 32,
+    :next => 0,
+    :prio => 230,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 156,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 200,
+    :tid => 228,
+    :timing_stack => 360,
+    :tls => 8,
+    :tls_base_context => 3404,
+    :world_age => 224,
+)
diff --git a/src/memlayout/linux-x86-v1_4_2.jl b/src/memlayout/linux-x86-v1_4_2.jl
new file mode 100644
index 00000000..fa408f34
--- /dev/null
+++ b/src/memlayout/linux-x86-v1_4_2.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("linux-x86", v"1.4.2")] = Dict(
+    :END => 364,
+    :backtrace => 28,
+    :bufsz => 204,
+    :copy_stack => 208,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 212,
+    :exception => 24,
+    :excstack => 220,
+    :gcstack => 216,
+    :locks => 232,
+    :logstate => 32,
+    :next => 0,
+    :prio => 230,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 156,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 200,
+    :tid => 228,
+    :timing_stack => 360,
+    :tls => 8,
+    :tls_base_context => 3404,
+    :world_age => 224,
+)
diff --git a/src/memlayout/linux-x86-v1_5_3.jl b/src/memlayout/linux-x86-v1_5_3.jl
new file mode 100644
index 00000000..a6da71f9
--- /dev/null
+++ b/src/memlayout/linux-x86-v1_5_3.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("linux-x86", v"1.5.3")] = Dict(
+    :END => 364,
+    :backtrace => 28,
+    :bufsz => 204,
+    :copy_stack => 208,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 212,
+    :exception => 24,
+    :excstack => 220,
+    :gcstack => 216,
+    :locks => 232,
+    :logstate => 32,
+    :next => 0,
+    :prio => 230,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 156,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 200,
+    :tid => 228,
+    :timing_stack => 360,
+    :tls => 8,
+    :tls_base_context => 3408,
+    :world_age => 224,
+)
diff --git a/src/memlayout/linux-x86-v1_5_4.jl b/src/memlayout/linux-x86-v1_5_4.jl
new file mode 100644
index 00000000..80d2bd9a
--- /dev/null
+++ b/src/memlayout/linux-x86-v1_5_4.jl
@@ -0,0 +1,27 @@
+ALL_TASK_OFFSETS[("linux-x86", v"1.5.4")] = Dict(
+    :END => 360,
+    :backtrace => 28,
+    :bufsz => 204,
+    :copy_stack => 208,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 212,
+    :exception => 24,
+    :excstack => 220,
+    :gcstack => 216,
+    :locks => 228,
+    :logstate => 32,
+    :next => 0,
+    :prio => 226,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 156,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 200,
+    :tid => 224,
+    :timing_stack => 356,
+    :tls => 8,
+    :tls_base_context => 3408,
+)
diff --git a/src/memlayout/linux-x86-v1_6_1.jl b/src/memlayout/linux-x86-v1_6_1.jl
new file mode 100644
index 00000000..8d04faee
--- /dev/null
+++ b/src/memlayout/linux-x86-v1_6_1.jl
@@ -0,0 +1,24 @@
+ALL_TASK_OFFSETS[("linux-x86", v"1.6.1")] = Dict(
+    :END => 216,
+    :_isexception => 30,
+    :_state => 28,
+    :bufsz => 204,
+    :copy_stack => 208,
+    :ctx => 44,
+    :donenotify => 12,
+    :eh => 40,
+    :excstack => 36,
+    :gcstack => 212,
+    :logstate => 20,
+    :next => 0,
+    :prio => 34,
+    :queue => 4,
+    :result => 16,
+    :sizeof_ctx => 156,
+    :start => 24,
+    :sticky => 29,
+    :stkbuf => 200,
+    :tid => 32,
+    :tls => 8,
+    :tls_base_context => 3412,
+)
diff --git a/src/memlayout/linux-x86-v1_8_0.jl b/src/memlayout/linux-x86-v1_8_0.jl
new file mode 100644
index 00000000..e681843b
--- /dev/null
+++ b/src/memlayout/linux-x86-v1_8_0.jl
@@ -0,0 +1,30 @@
+ALL_TASK_OFFSETS[("linux-x86", v"1.8.0")] = Dict(
+    :END => 256,
+    :_isexception => 30,
+    :_state => 28,
+    :bufsz => 248,
+    :copy_stack => 252,
+    :ctx => 88,
+    :donenotify => 12,
+    :eh => 84,
+    :excstack => 80,
+    :gcstack => 64,
+    :logstate => 20,
+    :next => 0,
+    :prio => 78,
+    :ptls => 72,
+    :queue => 4,
+    :result => 16,
+    :rngState0 => 32,
+    :rngState1 => 40,
+    :rngState2 => 48,
+    :rngState3 => 56,
+    :sizeof_ctx => 156,
+    :start => 24,
+    :sticky => 29,
+    :stkbuf => 244,
+    :tid => 76,
+    :tls => 8,
+    :tls_base_context => 3416,
+    :world_age => 68,
+)
diff --git a/src/memlayout/linux-x86_64-v1_3_1.jl b/src/memlayout/linux-x86_64-v1_3_1.jl
new file mode 100644
index 00000000..cca19241
--- /dev/null
+++ b/src/memlayout/linux-x86_64-v1_3_1.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("linux-x86_64", v"1.3.1")] = Dict(
+    :END => 616,
+    :backtrace => 56,
+    :bufsz => 296,
+    :copy_stack => 304,
+    :ctx => 88,
+    :donenotify => 32,
+    :eh => 312,
+    :exception => 48,
+    :excstack => 328,
+    :gcstack => 320,
+    :locks => 352,
+    :logstate => 64,
+    :next => 0,
+    :prio => 346,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 200,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 288,
+    :tid => 344,
+    :timing_stack => 608,
+    :tls => 16,
+    :tls_base_context => 6640,
+    :world_age => 336,
+)
diff --git a/src/memlayout/linux-x86_64-v1_4_2.jl b/src/memlayout/linux-x86_64-v1_4_2.jl
new file mode 100644
index 00000000..6a1cc083
--- /dev/null
+++ b/src/memlayout/linux-x86_64-v1_4_2.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("linux-x86_64", v"1.4.2")] = Dict(
+    :END => 616,
+    :backtrace => 56,
+    :bufsz => 296,
+    :copy_stack => 304,
+    :ctx => 88,
+    :donenotify => 32,
+    :eh => 312,
+    :exception => 48,
+    :excstack => 328,
+    :gcstack => 320,
+    :locks => 352,
+    :logstate => 64,
+    :next => 0,
+    :prio => 346,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 200,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 288,
+    :tid => 344,
+    :timing_stack => 608,
+    :tls => 16,
+    :tls_base_context => 6640,
+    :world_age => 336,
+)
diff --git a/src/memlayout/linux-x86_64-v1_5_3.jl b/src/memlayout/linux-x86_64-v1_5_3.jl
new file mode 100644
index 00000000..2e92d6d7
--- /dev/null
+++ b/src/memlayout/linux-x86_64-v1_5_3.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("linux-x86_64", v"1.5.3")] = Dict(
+    :END => 616,
+    :backtrace => 56,
+    :bufsz => 296,
+    :copy_stack => 304,
+    :ctx => 88,
+    :donenotify => 32,
+    :eh => 312,
+    :exception => 48,
+    :excstack => 328,
+    :gcstack => 320,
+    :locks => 352,
+    :logstate => 64,
+    :next => 0,
+    :prio => 346,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 200,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 288,
+    :tid => 344,
+    :timing_stack => 608,
+    :tls => 16,
+    :tls_base_context => 6648,
+    :world_age => 336,
+)
diff --git a/src/memlayout/linux-x86_64-v1_5_4.jl b/src/memlayout/linux-x86_64-v1_5_4.jl
new file mode 100644
index 00000000..505955d0
--- /dev/null
+++ b/src/memlayout/linux-x86_64-v1_5_4.jl
@@ -0,0 +1,27 @@
+ALL_TASK_OFFSETS[("linux-x86_64", v"1.5.4")] = Dict(
+    :END => 608,
+    :backtrace => 56,
+    :bufsz => 296,
+    :copy_stack => 304,
+    :ctx => 88,
+    :donenotify => 32,
+    :eh => 312,
+    :exception => 48,
+    :excstack => 328,
+    :gcstack => 320,
+    :locks => 344,
+    :logstate => 64,
+    :next => 0,
+    :prio => 338,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 200,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 288,
+    :tid => 336,
+    :timing_stack => 600,
+    :tls => 16,
+    :tls_base_context => 6648,
+)
diff --git a/src/memlayout/linux-x86_64-v1_6_1.jl b/src/memlayout/linux-x86_64-v1_6_1.jl
new file mode 100644
index 00000000..adbe2774
--- /dev/null
+++ b/src/memlayout/linux-x86_64-v1_6_1.jl
@@ -0,0 +1,24 @@
+ALL_TASK_OFFSETS[("linux-x86_64", v"1.6.1")] = Dict(
+    :END => 312,
+    :_isexception => 58,
+    :_state => 56,
+    :bufsz => 288,
+    :copy_stack => 296,
+    :ctx => 80,
+    :donenotify => 24,
+    :eh => 72,
+    :excstack => 64,
+    :gcstack => 304,
+    :logstate => 40,
+    :next => 0,
+    :prio => 62,
+    :queue => 8,
+    :result => 32,
+    :sizeof_ctx => 200,
+    :start => 48,
+    :sticky => 57,
+    :stkbuf => 280,
+    :tid => 60,
+    :tls => 16,
+    :tls_base_context => 6656,
+)
diff --git a/src/memlayout/linux-x86_64-v1_8_0.jl b/src/memlayout/linux-x86_64-v1_8_0.jl
new file mode 100644
index 00000000..6b2a97ce
--- /dev/null
+++ b/src/memlayout/linux-x86_64-v1_8_0.jl
@@ -0,0 +1,30 @@
+ALL_TASK_OFFSETS[("linux-x86_64", v"1.8.0")] = Dict(
+    :END => 368,
+    :_isexception => 58,
+    :_state => 56,
+    :bufsz => 352,
+    :copy_stack => 360,
+    :ctx => 144,
+    :donenotify => 24,
+    :eh => 136,
+    :excstack => 128,
+    :gcstack => 96,
+    :logstate => 40,
+    :next => 0,
+    :prio => 122,
+    :ptls => 112,
+    :queue => 8,
+    :result => 32,
+    :rngState0 => 64,
+    :rngState1 => 72,
+    :rngState2 => 80,
+    :rngState3 => 88,
+    :sizeof_ctx => 200,
+    :start => 48,
+    :sticky => 57,
+    :stkbuf => 344,
+    :tid => 120,
+    :tls => 16,
+    :tls_base_context => 6656,
+    :world_age => 104,
+)
diff --git a/src/memlayout/main.jl b/src/memlayout/main.jl
new file mode 100644
index 00000000..169cc93a
--- /dev/null
+++ b/src/memlayout/main.jl
@@ -0,0 +1,106 @@
+const ALL_TASK_OFFSETS =
+    Dict{Tuple{String, VersionNumber}, Dict{Symbol, Int}}()
+
+
+include("linux-x86-v1_3_1.jl")
+include("linux-x86-v1_4_2.jl")
+include("linux-x86-v1_5_3.jl")
+include("linux-x86-v1_5_4.jl")
+include("linux-x86-v1_6_1.jl")
+include("linux-x86-v1_8_0.jl")
+
+include("linux-x86_64-v1_3_1.jl")
+include("linux-x86_64-v1_4_2.jl")
+include("linux-x86_64-v1_5_3.jl")
+include("linux-x86_64-v1_5_4.jl")
+include("linux-x86_64-v1_6_1.jl")
+include("linux-x86_64-v1_8_0.jl")
+
+include("darwin-x86_64-v1_3_1.jl")
+include("darwin-x86_64-v1_4_2.jl")
+include("darwin-x86_64-v1_5_3.jl")
+include("darwin-x86_64-v1_5_4.jl")
+include("darwin-x86_64-v1_6_1.jl")
+
+include("windows-x86-v1_3_1.jl")
+include("windows-x86-v1_4_2.jl")
+include("windows-x86-v1_5_3.jl")
+include("windows-x86-v1_5_4.jl")
+include("windows-x86-v1_6_1.jl")
+
+include("windows-x86_64-v1_3_1.jl")
+include("windows-x86_64-v1_4_2.jl")
+include("windows-x86_64-v1_5_3.jl")
+include("windows-x86_64-v1_5_4.jl")
+include("windows-x86_64-v1_6_1.jl")
+
+const ARCH = @static if string(Sys.ARCH)[1] == 'i'
+    "x86"
+else
+    string(Sys.ARCH)
+end
+
+const PLATFORM = @static if Sys.islinux()
+    "linux-" * ARCH
+elseif Sys.iswindows()
+    "windows-" * ARCH
+elseif Sys.isapple()
+    "darwin-" * ARCH
+end
+
+function find_offsets()
+    candi = [v for (p, v) in keys(ALL_TASK_OFFSETS) if p == PLATFORM]
+    sort!(candi)
+    candi = [v for v in candi if v <= VERSION]
+    isempty(candi) && error("No suitable offsets")
+    ALL_TASK_OFFSETS[(PLATFORM, candi[end])]
+end
+
+const TASK_OFFSETS = find_offsets()
+
+## utilities
+
+# getter
+function internal_getfield(task, field, ::Type{Ptr})
+    ccall((:jl_getfield_ptr, libtask_julia),
+          Ptr{Cvoid}, (Any, Csize_t),
+          task, TASK_OFFSETS[field])
+end
+
+function internal_getfield(task, field, ::Type{Int32})
+    ccall((:jl_getfield_int32_t, libtask_julia),
+          Int32, (Any, Csize_t), task, TASK_OFFSETS[field])
+end
+
+# setter
+function internal_setfield(task, field, ::Nothing)
+    haskey(TASK_OFFSETS, field) && ccall(
+        (:jl_setfield_nothing, libtask_julia),
+        Any, (Any, Csize_t), task, TASK_OFFSETS[field])
+end
+
+function internal_setfield(task, field, p::Ptr{Nothing})
+    p == C_NULL || error("this function is only for setting NULL value")
+    haskey(TASK_OFFSETS, field) && ccall(
+        (:jl_setfield_null, libtask_julia),
+        Any, (Any, Csize_t), task, TASK_OFFSETS[field])
+end
+
+function internal_setfield(task, field, val::Csize_t)
+    ccall((:jl_setfield_size_t, libtask_julia),
+          Any, (Any, Csize_t, Csize_t),
+          task, TASK_OFFSETS[field], val)
+end
+
+function internal_setfield(task, field, val::Int32)
+    ccall((:jl_setfield_int32_t, libtask_julia),
+          Any, (Any, Csize_t, Int32),
+          task, TASK_OFFSETS[field], val)
+end
+
+function memset(task, val, offset_field; end_field=:END)
+    haskey(TASK_OFFSETS, offset_field) && ccall(
+        (:jl_memset, libtask_julia),
+        Cvoid, (Any, Csize_t, Csize_t, Int),
+        task, TASK_OFFSETS[offset_field], TASK_OFFSETS[end_field], val)
+end
diff --git a/src/memlayout/windows-x86-v1_3_1.jl b/src/memlayout/windows-x86-v1_3_1.jl
new file mode 100644
index 00000000..6fe2d316
--- /dev/null
+++ b/src/memlayout/windows-x86-v1_3_1.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("windows-x86", v"1.3.1")] = Dict(
+    :END => 280,
+    :backtrace => 28,
+    :bufsz => 120,
+    :copy_stack => 124,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 128,
+    :exception => 24,
+    :excstack => 136,
+    :gcstack => 132,
+    :locks => 148,
+    :logstate => 32,
+    :next => 0,
+    :prio => 146,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 72,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 116,
+    :tid => 144,
+    :timing_stack => 276,
+    :tls => 8,
+    :tls_base_context => 3352,
+    :world_age => 140,
+)
diff --git a/src/memlayout/windows-x86-v1_4_2.jl b/src/memlayout/windows-x86-v1_4_2.jl
new file mode 100644
index 00000000..1f502163
--- /dev/null
+++ b/src/memlayout/windows-x86-v1_4_2.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("windows-x86", v"1.4.2")] = Dict(
+    :END => 280,
+    :backtrace => 28,
+    :bufsz => 120,
+    :copy_stack => 124,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 128,
+    :exception => 24,
+    :excstack => 136,
+    :gcstack => 132,
+    :locks => 148,
+    :logstate => 32,
+    :next => 0,
+    :prio => 146,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 72,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 116,
+    :tid => 144,
+    :timing_stack => 276,
+    :tls => 8,
+    :tls_base_context => 3352,
+    :world_age => 140,
+)
diff --git a/src/memlayout/windows-x86-v1_5_3.jl b/src/memlayout/windows-x86-v1_5_3.jl
new file mode 100644
index 00000000..7c73b7a8
--- /dev/null
+++ b/src/memlayout/windows-x86-v1_5_3.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("windows-x86", v"1.5.3")] = Dict(
+    :END => 280,
+    :backtrace => 28,
+    :bufsz => 120,
+    :copy_stack => 124,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 128,
+    :exception => 24,
+    :excstack => 136,
+    :gcstack => 132,
+    :locks => 148,
+    :logstate => 32,
+    :next => 0,
+    :prio => 146,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 72,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 116,
+    :tid => 144,
+    :timing_stack => 276,
+    :tls => 8,
+    :tls_base_context => 3356,
+    :world_age => 140,
+)
diff --git a/src/memlayout/windows-x86-v1_5_4.jl b/src/memlayout/windows-x86-v1_5_4.jl
new file mode 100644
index 00000000..53f9c6dc
--- /dev/null
+++ b/src/memlayout/windows-x86-v1_5_4.jl
@@ -0,0 +1,27 @@
+ALL_TASK_OFFSETS[("windows-x86", v"1.5.4")] = Dict(
+    :END => 276,
+    :backtrace => 28,
+    :bufsz => 120,
+    :copy_stack => 124,
+    :ctx => 44,
+    :donenotify => 16,
+    :eh => 128,
+    :exception => 24,
+    :excstack => 136,
+    :gcstack => 132,
+    :locks => 144,
+    :logstate => 32,
+    :next => 0,
+    :prio => 142,
+    :queue => 4,
+    :result => 20,
+    :sizeof_ctx => 72,
+    :start => 36,
+    :state => 12,
+    :sticky => 40,
+    :stkbuf => 116,
+    :tid => 140,
+    :timing_stack => 272,
+    :tls => 8,
+    :tls_base_context => 3356,
+)
diff --git a/src/memlayout/windows-x86-v1_6_1.jl b/src/memlayout/windows-x86-v1_6_1.jl
new file mode 100644
index 00000000..2b1f3750
--- /dev/null
+++ b/src/memlayout/windows-x86-v1_6_1.jl
@@ -0,0 +1,24 @@
+ALL_TASK_OFFSETS[("windows-x86", v"1.6.1")] = Dict(
+    :END => 132,
+    :_isexception => 30,
+    :_state => 28,
+    :bufsz => 120,
+    :copy_stack => 124,
+    :ctx => 44,
+    :donenotify => 12,
+    :eh => 40,
+    :excstack => 36,
+    :gcstack => 128,
+    :logstate => 20,
+    :next => 0,
+    :prio => 34,
+    :queue => 4,
+    :result => 16,
+    :sizeof_ctx => 72,
+    :start => 24,
+    :sticky => 29,
+    :stkbuf => 116,
+    :tid => 32,
+    :tls => 8,
+    :tls_base_context => 3360,
+)
diff --git a/src/memlayout/windows-x86_64-v1_3_1.jl b/src/memlayout/windows-x86_64-v1_3_1.jl
new file mode 100644
index 00000000..1669f3f8
--- /dev/null
+++ b/src/memlayout/windows-x86_64-v1_3_1.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("windows-x86_64", v"1.3.1")] = Dict(
+    :END => 704,
+    :backtrace => 56,
+    :bufsz => 376,
+    :copy_stack => 384,
+    :ctx => 96,
+    :donenotify => 32,
+    :eh => 392,
+    :exception => 48,
+    :excstack => 408,
+    :gcstack => 400,
+    :locks => 432,
+    :logstate => 64,
+    :next => 0,
+    :prio => 426,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 272,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 368,
+    :tid => 424,
+    :timing_stack => 688,
+    :tls => 16,
+    :tls_base_context => 6608,
+    :world_age => 416,
+)
diff --git a/src/memlayout/windows-x86_64-v1_4_2.jl b/src/memlayout/windows-x86_64-v1_4_2.jl
new file mode 100644
index 00000000..504caa71
--- /dev/null
+++ b/src/memlayout/windows-x86_64-v1_4_2.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("windows-x86_64", v"1.4.2")] = Dict(
+    :END => 704,
+    :backtrace => 56,
+    :bufsz => 376,
+    :copy_stack => 384,
+    :ctx => 96,
+    :donenotify => 32,
+    :eh => 392,
+    :exception => 48,
+    :excstack => 408,
+    :gcstack => 400,
+    :locks => 432,
+    :logstate => 64,
+    :next => 0,
+    :prio => 426,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 272,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 368,
+    :tid => 424,
+    :timing_stack => 688,
+    :tls => 16,
+    :tls_base_context => 6608,
+    :world_age => 416,
+)
diff --git a/src/memlayout/windows-x86_64-v1_5_3.jl b/src/memlayout/windows-x86_64-v1_5_3.jl
new file mode 100644
index 00000000..07d4ebae
--- /dev/null
+++ b/src/memlayout/windows-x86_64-v1_5_3.jl
@@ -0,0 +1,28 @@
+ALL_TASK_OFFSETS[("windows-x86_64", v"1.5.3")] = Dict(
+    :END => 704,
+    :backtrace => 56,
+    :bufsz => 376,
+    :copy_stack => 384,
+    :ctx => 96,
+    :donenotify => 32,
+    :eh => 392,
+    :exception => 48,
+    :excstack => 408,
+    :gcstack => 400,
+    :locks => 432,
+    :logstate => 64,
+    :next => 0,
+    :prio => 426,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 272,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 368,
+    :tid => 424,
+    :timing_stack => 688,
+    :tls => 16,
+    :tls_base_context => 6608,
+    :world_age => 416,
+)
diff --git a/src/memlayout/windows-x86_64-v1_5_4.jl b/src/memlayout/windows-x86_64-v1_5_4.jl
new file mode 100644
index 00000000..446c1396
--- /dev/null
+++ b/src/memlayout/windows-x86_64-v1_5_4.jl
@@ -0,0 +1,27 @@
+ALL_TASK_OFFSETS[("windows-x86_64", v"1.5.4")] = Dict(
+    :END => 688,
+    :backtrace => 56,
+    :bufsz => 376,
+    :copy_stack => 384,
+    :ctx => 96,
+    :donenotify => 32,
+    :eh => 392,
+    :exception => 48,
+    :excstack => 408,
+    :gcstack => 400,
+    :locks => 424,
+    :logstate => 64,
+    :next => 0,
+    :prio => 418,
+    :queue => 8,
+    :result => 40,
+    :sizeof_ctx => 272,
+    :start => 72,
+    :state => 24,
+    :sticky => 80,
+    :stkbuf => 368,
+    :tid => 416,
+    :timing_stack => 680,
+    :tls => 16,
+    :tls_base_context => 6608,
+)
diff --git a/src/memlayout/windows-x86_64-v1_6_1.jl b/src/memlayout/windows-x86_64-v1_6_1.jl
new file mode 100644
index 00000000..6640becd
--- /dev/null
+++ b/src/memlayout/windows-x86_64-v1_6_1.jl
@@ -0,0 +1,24 @@
+ALL_TASK_OFFSETS[("windows-x86_64", v"1.6.1")] = Dict(
+    :END => 384,
+    :_isexception => 58,
+    :_state => 56,
+    :bufsz => 360,
+    :copy_stack => 368,
+    :ctx => 80,
+    :donenotify => 24,
+    :eh => 72,
+    :excstack => 64,
+    :gcstack => 376,
+    :logstate => 40,
+    :next => 0,
+    :prio => 62,
+    :queue => 8,
+    :result => 32,
+    :sizeof_ctx => 272,
+    :start => 48,
+    :sticky => 57,
+    :stkbuf => 352,
+    :tid => 60,
+    :tls => 16,
+    :tls_base_context => 6624,
+)