diff --git a/' b/'
new file mode 100644
index 0000000..cac9b8d
--- /dev/null
+++ b/'
@@ -0,0 +1,131 @@
+#include "sled/strings/utils.h"
+#include <sstream>
+#include <string.h>
+
+namespace sled {
+
+char
+ToLower(char c)
+{
+    return ::tolower(c);
+}
+
+char
+ToUpper(char c)
+{
+    return ::toupper(c);
+}
+
+std::string
+ToLower(const std::string &str)
+{
+    std::stringstream ss;
+    for (auto &ch : str) { ss << ToLower(ch); }
+    return ss.str();
+}
+
+std::string
+ToUpper(const std::string &str)
+{
+    std::stringstream ss;
+    for (auto &ch : str) { ss << ToUpper(ch); }
+    return ss.str();
+}
+
+std::string
+StrJoin(const std::vector<std::string> &strings, const std::string &delim, bool skip_empty)
+{
+    if (strings.empty()) { return ""; }
+
+    std::stringstream ss;
+    size_t i = 0;
+    while (skip_empty && i < strings.size() && strings[i].empty()) { ++i; }
+    if (i < strings.size()) { ss << strings[i++]; }
+    for (; i < strings.size(); ++i) {
+        if (skip_empty && strings[i].empty()) { continue; }
+        ss << delim << strings[i];
+    }
+    return ss.str();
+}
+
+std::vector<std::string>
+StrSplit(const std::string &str, const std::string &delim, bool skip_empty)
+{
+    std::vector<std::string> result;
+    if (str.empty()) { return result; }
+
+    size_t start    = 0;
+    size_t next_pos = str.find_first_of(delim, start);
+    while (next_pos != std::string::npos) {
+        if ((!skip_empty && next_pos == start) || next_pos > start) {
+            result.emplace_back(str.begin() + start, str.begin() + next_pos);
+        }
+
+        if (!skip_empty) {
+            start    = next_pos + 1;
+            next_pos = str.find_first_of(delim, start);
+        } else {
+            start = str.find_first_not_of(delim, next_pos);
+            if (start == std::string::npos) {
+                // all remaining characters are delimiters
+                break;
+            }
+            next_pos = str.find_first_of(delim, start);
+        }
+    }
+
+    if (start < str.size()) { result.emplace_back(str.substr(start)); }
+    return result;
+}
+
+std::string
+Trim(const std::string &str, const std::string &chars)
+{
+    return TrimLeft(TrimRight(str, chars), chars);
+}
+
+std::string
+TrimLeft(const std::string &str, const std::string &chars)
+{
+    size_t start = str.find_first_not_of(chars);
+    return start == std::string::npos ? "" : str.substr(start);
+}
+
+std::string
+TrimRight(const std::string &str, const std::string &chars)
+{
+    size_t end = str.find_last_not_of(chars);
+    return end == std::string::npos ? "" : str.substr(0, end + 1);
+}
+
+bool
+EndsWith(const std::string &str, const std::string &suffix)
+{
+    return str.size() >= suffix.size() && str.compare(str.size() - suffix.size(), suffix.size(), suffix) == 0;
+}
+
+bool
+StartsWith(const std::string &str, const std::string &prefix)
+{
+    return str.size() >= prefix.size() && str.compare(0, prefix.size(), prefix) == 0;
+}
+
+bool
+EndsWithIgnoreCase(const std::string &str, const std::string &suffix)
+{
+    return EndsWith(ToLower(str), ToLower(suffix));
+}
+
+bool
+StartsWithIgnoreCase(const std::string &str, const std::string &prefix)
+{
+    return StartsWith(ToLower(str), ToLower(prefix));
+}
+
+bool
+EqualsIgnoreCase(const std::string &lhs, const std::string &rhs)
+{
+    return ToLower(lhs) == ToLower(rhs);
+}
+
+}// namespace sled
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 28566a2..3f08e74 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -45,6 +45,7 @@ target_include_directories(sled PUBLIC src/ 3party/eigen 3party/inja
 target_sources(
   sled
   PRIVATE src/sled/async/async.cc
+          src/sled/debugging/symbolize.cc
           src/sled/filesystem/path.cc
           src/sled/log/log.cc
           src/sled/network/async_resolver.cc
@@ -112,6 +113,32 @@ if(SLED_BUILD_BENCHMARK)
                                                benchmark::benchmark_main)
 endif(SLED_BUILD_BENCHMARK)
 
+function(sled_add_test)
+  set(prefix SLED_TEST)
+  # set(options INC_DIRS LIBS)
+  set(one_value_keywords NAME)
+  set(multi_value_keywords SRCS INC_DIRS LIBS)
+  cmake_parse_arguments("${prefix}" "${options}" "${one_value_keywords}"
+                        "${multi_value_keywords}" ${ARGN})
+
+  message(WARNING "SLED_TEST_NAME: ${SLED_TEST_NAME}")
+  message(WARNING "SLED_TEST_SRCS: ${SLED_TEST_SRCS}")
+  message(WARNING "SLED_TEST_LIBS: ${SLED_TEST_LIBS}")
+  add_executable(${SLED_TEST_NAME} ${SLED_TEST_SRCS})
+
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    set(EXTRA_FLAGS -Wthread-safety -g -fsanitize=address
+                    -fno-omit-frame-pointer -fno-optimize-sibling-calls)
+    target_compile_options(${SLED_TEST_NAME} PRIVATE ${EXTRA_FLAGS})
+
+    target_link_options(${SLED_TEST_NAME} PRIVATE ${EXTRA_FLAGS})
+  endif()
+  target_include_directories(${SLED_TEST_NAME} PRIVATE ${SLED_TEST_INC_DIRS})
+  target_link_libraries(${SLED_TEST_NAME} PRIVATE ${SLED_TEST_LIBS}
+                                                  GTest::gtest)
+  add_test(NAME ${SLED_TEST_NAME} COMMAND ${SLED_TEST_NAME})
+endfunction()
+
 if(SLED_BUILD_TESTS)
   include(FetchContent)
   FetchContent_Declare(
@@ -119,17 +146,16 @@ if(SLED_BUILD_TESTS)
     URL https://github.com/google/googletest/archive/03597a01ee50ed33e9dfd640b249b4be3799d395.zip
   )
   FetchContent_MakeAvailable(googletest)
-  add_executable(
-    sled_tests
-    # src/sled/exec/just_test.cc
+
+  sled_add_test(
+    NAME
+    sled_base_test
+    SRCS
     src/sled/async/async_test.cc
     src/sled/any_test.cc
     src/sled/filesystem/path_test.cc
-    # src/sled/futures/promise_test.cc
     src/sled/futures/detail/just_test.cc
     src/sled/log/fmt_test.cc
-    # src/sled/profiling/profiling_test.cc
-    src/sled/strings/base64_test.cc
     src/sled/synchronization/sequence_checker_test.cc
     src/sled/cleanup_test.cc
     src/sled/status_test.cc
@@ -137,16 +163,23 @@ if(SLED_BUILD_TESTS)
     src/sled/system/fiber/fiber_test.cc
     src/sled/system/thread_pool_test.cc
     src/sled/rx_test.cc
-    src/sled/uri_test.cc)
-  if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-    set(EXTRA_FLAGS -Wthread-safety -g -fsanitize=address
-                    -fno-omit-frame-pointer -fno-optimize-sibling-calls)
-    target_compile_options(sled_tests PRIVATE ${EXTRA_FLAGS})
+    src/sled/uri_test.cc
+    LIBS
+    sled
+    GTest::gtest_main)
 
-    target_link_options(sled_tests PRIVATE ${EXTRA_FLAGS})
-  endif()
-  target_link_libraries(sled_tests PRIVATE sled GTest::gtest GTest::gtest_main)
-  add_test(NAME sled_tests COMMAND sled_tests)
+  sled_add_test(
+    NAME
+    sled_strings_test
+    SRCS
+    src/sled/strings/utils_test.cc
+    src/sled/strings/base64_test.cc
+    LIBS
+    sled
+    GTest::gtest_main)
+
+  sled_add_test(NAME sled_symbolize_test SRCS
+                src/sled/debugging/symbolize_test.cc LIBS sled)
 endif(SLED_BUILD_TESTS)
 
 if(SLED_BUILD_FUZZ)
diff --git a/src/sled/debugging/symbolize.cc b/src/sled/debugging/symbolize.cc
new file mode 100644
index 0000000..b3d024c
--- /dev/null
+++ b/src/sled/debugging/symbolize.cc
@@ -0,0 +1,25 @@
+#include "sled/debugging/symbolize.h"
+
+#ifdef _WIN32
+void
+InitializeSymbolizer(const char *argv0)
+{}
+
+bool
+Symbolize(const void *pc, char *out, int out_size)
+{
+    return false;
+}
+#elif defined(__APPLE__)
+void
+InitializeSymbolizer(const char *argv0)
+{}
+
+bool
+Symbolize(const void *pc, char *out, int out_size)
+{
+    return false;
+}
+#elif defined(__linux__)
+#include "sled/debugging/symbolize_elf.inc"
+#endif
diff --git a/src/sled/debugging/symbolize.h b/src/sled/debugging/symbolize.h
new file mode 100644
index 0000000..9f3b89a
--- /dev/null
+++ b/src/sled/debugging/symbolize.h
@@ -0,0 +1,10 @@
+#ifndef SLED_DEBUGGING_SYMBOLIZE_H
+#define SLED_DEBUGGING_SYMBOLIZE_H
+#pragma once
+
+namespace sled {
+void InitializeSymbolizer(const char *argv0);
+bool Symbolize(const void *pc, char *out, int out_size);
+bool ReadAddrMap();
+}// namespace sled
+#endif// SLED_DEBUGGING_SYMBOLIZE_H
diff --git a/src/sled/debugging/symbolize_elf.inc b/src/sled/debugging/symbolize_elf.inc
new file mode 100644
index 0000000..ab51283
--- /dev/null
+++ b/src/sled/debugging/symbolize_elf.inc
@@ -0,0 +1,140 @@
+#include <array>
+#include <cxxabi.h>
+#include <dlfcn.h>
+#include <elf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <link.h>
+#include <sled/log/log.h>
+#include <sled/strings/utils.h>
+#include <sstream>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+namespace sled {
+
+static constexpr char kTag[] = "symbolizer";
+static char *g_exe           = nullptr;
+
+static const uint64_t
+GetHex(const char *start, const char *end)
+{
+    uint64_t hex = 0;
+    for (const char *p = start; p < end; ++p) {
+        int ch = *p;
+        if (ch >= '0' && ch <= '9') {
+            hex = hex * 16 + (ch - '0');
+        } else if (ch >= 'a' && ch <= 'f') {
+            hex = hex * 16 + (ch - 'a' + 10);
+        } else if (ch >= 'A' && ch <= 'F') {
+            hex = hex * 16 + (ch - 'A' + 10);
+        } else {
+            break;
+        }
+    }
+
+    return hex;
+}
+
+static const uint64_t
+GetHex(const std::string &str)
+{
+    return GetHex(str.c_str(), str.c_str() + str.size());
+}
+
+struct ObjFile {
+    ObjFile() : filename(nullptr), start_addr(nullptr), end_addr(nullptr), offset(0), fd(-1), elf_type(-1)
+    {
+        memset(&elf_header, 0, sizeof(elf_header));
+        memset(phdrs.data(), 0, sizeof(ElfW(Phdr)) * phdrs.size());
+    }
+
+    char *filename;
+    const void *start_addr;
+    const void *end_addr;
+    uint64_t offset;
+
+    int fd;
+    int elf_type;
+    ElfW(Ehdr) elf_header;
+
+    std::array<ElfW(Phdr), 16> phdrs;
+};
+
+std::string
+ReadFullFile(int fd)
+{
+    std::stringstream ss;
+    char buf[4096];
+    ssize_t n;
+    while ((n = read(fd, buf, sizeof(buf))) > 0) { ss.write(buf, n); }
+    return ss.str();
+}
+
+bool
+ReadAddrMap()
+{
+    char maps_path[80];
+    snprintf(maps_path, sizeof(maps_path), "/proc/self/task/%d/maps", getpid());
+    int maps_fd;
+    do {
+        maps_fd = open(maps_path, O_RDONLY);
+    } while (maps_fd < 0 && errno == EINTR);
+
+    if (maps_fd < 0) {
+        LOGE(kTag, "open {} failed, {}", maps_path, strerror(errno));
+        return false;
+    }
+
+    std::string full_file = ReadFullFile(maps_fd);
+    auto lines            = sled::StrSplit(full_file, "\n");
+
+    // maps start_addr-end_addr permission offset dev inode pathname
+    for (const auto &line : lines) {
+        auto fields = sled::StrSplit(line, " \n\t", true);
+        if (fields.size() < 6) { continue; }
+        auto addrs = sled::StrSplit(fields[0], "-", false);
+
+        uint64_t start_addr = GetHex(addrs[0]);
+        uint64_t end_addr   = GetHex(addrs[1]);
+        uint64_t offset     = GetHex(fields[2]);
+        LOGD(kTag, "addr: {}-{} {} {} {}", start_addr, end_addr, offset, fields[1], fields[5]);
+    }
+
+    return true;
+}
+
+class Symbolizer {};
+
+void
+InitializeSymbolizer(const char *argv0)
+{
+    if (g_exe) {
+        free(g_exe);
+        g_exe = nullptr;
+    }
+
+    if (argv0 && argv0[0] != '\0') { g_exe = strdup(argv0); }
+}
+
+bool
+Symbolize(const void *pc, char *out, int out_size)
+{
+    Dl_info info;
+    if (!dladdr(pc, &info)) { return false; }
+    if (info.dli_fname && out_size > 0) {
+        strncpy(out, info.dli_fname, out_size);
+
+        const auto end_pos = static_cast<size_t>(out_size) - 1;
+        if (out[end_pos] != '\0') {
+            // add ...
+            out[end_pos] = '\0';
+        }
+    }
+
+    return true;
+}
+}// namespace sled
diff --git a/src/sled/debugging/symbolize_test.cc b/src/sled/debugging/symbolize_test.cc
new file mode 100644
index 0000000..8a5272a
--- /dev/null
+++ b/src/sled/debugging/symbolize_test.cc
@@ -0,0 +1,43 @@
+#include <gtest/gtest.h>
+#include <sled/debugging/symbolize.h>
+#include <sled/make_unique.h>
+
+void
+TestFunc1()
+{}
+
+static char try_symbolize_buffer[4096];
+
+static const char *
+TrySymbolizeWithLimit(void *pc, int limit)
+{
+    // ASSERT_LE(limit, 4096);
+    auto heap_buffer = sled::MakeUnique<char[]>(4096);
+    bool found       = sled::Symbolize(pc, heap_buffer.get(), sizeof(try_symbolize_buffer));
+    strncpy(try_symbolize_buffer, heap_buffer.get(), sizeof(try_symbolize_buffer) - 1);
+    try_symbolize_buffer[sizeof(try_symbolize_buffer) - 1] = '\0';
+
+    return try_symbolize_buffer;
+}
+
+static const char *
+TrySymbolize(void *pc)
+{
+    return TrySymbolizeWithLimit(pc, 4096);
+}
+
+// TEST(Symbolize, base)
+// {
+//     char buf[1024];
+//     EXPECT_EQ("TestFunc1", TrySymbolize((void *) &TestFunc1));
+// }
+
+TEST(Symbolize, ReadAddrMap) { sled::ReadAddrMap(); }
+
+int
+main(int argc, char *argv[])
+{
+    sled::InitializeSymbolizer(argv[0]);
+    testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
diff --git a/src/sled/strings/utils.cc b/src/sled/strings/utils.cc
index c41658b..dd40eca 100644
--- a/src/sled/strings/utils.cc
+++ b/src/sled/strings/utils.cc
@@ -54,15 +54,31 @@ StrSplit(const std::string &str, const std::string &delim, bool skip_empty)
     std::vector<std::string> result;
     if (str.empty()) { return result; }
 
-    size_t start = 0;
+    size_t start    = 0;
     size_t next_pos = str.find_first_of(delim, start);
     while (next_pos != std::string::npos) {
-        if (!skip_empty || next_pos > start) { result.emplace_back(str.substr(start, next_pos - start)); }
-        start = next_pos + 1;
-        next_pos = str.find_first_of(delim, start);
+        if ((!skip_empty && next_pos == start) || next_pos > start) {
+            result.emplace_back(str.begin() + start, str.begin() + next_pos);
+        }
+
+        if (!skip_empty) {
+            start    = next_pos + 1;
+            next_pos = str.find_first_of(delim, start);
+        } else {
+            start = str.find_first_not_of(delim, next_pos);
+            if (start == std::string::npos) {
+                // all remaining characters are delimiters
+                break;
+            }
+            next_pos = str.find_first_of(delim, start);
+        }
     }
 
-    if (start < str.size()) { result.emplace_back(str.substr(start)); }
+    if (start < str.size()) {
+        result.emplace_back(str.substr(start));
+    } else if (!skip_empty && !str.empty() && delim.find(str.back()) != std::string::npos) {
+        result.emplace_back("");
+    }
     return result;
 }
 
diff --git a/src/sled/strings/utils_test.cc b/src/sled/strings/utils_test.cc
new file mode 100644
index 0000000..7d2f7ce
--- /dev/null
+++ b/src/sled/strings/utils_test.cc
@@ -0,0 +1,99 @@
+#include <gtest/gtest.h>
+#include <sled/strings/utils.h>
+
+TEST(ToLower, Char)
+{
+    EXPECT_EQ(sled::ToLower('A'), 'a');
+    EXPECT_EQ(sled::ToLower('Z'), 'z');
+    EXPECT_EQ(sled::ToLower('a'), 'a');
+    EXPECT_EQ(sled::ToLower('z'), 'z');
+    EXPECT_EQ(sled::ToLower(' '), ' ');
+    EXPECT_EQ(sled::ToLower('\0'), '\0');
+}
+
+TEST(ToUpper, Char)
+{
+    EXPECT_EQ(sled::ToUpper('A'), 'A');
+    EXPECT_EQ(sled::ToUpper('Z'), 'Z');
+    EXPECT_EQ(sled::ToUpper('a'), 'A');
+    EXPECT_EQ(sled::ToUpper('z'), 'Z');
+    EXPECT_EQ(sled::ToUpper(' '), ' ');
+    EXPECT_EQ(sled::ToUpper('\0'), '\0');
+}
+
+TEST(ToLower, String)
+{
+    EXPECT_EQ(sled::ToLower("Hello World"), "hello world");
+    EXPECT_EQ(sled::ToLower("HELLO WORLD"), "hello world");
+    EXPECT_EQ(sled::ToLower("hello world"), "hello world");
+    EXPECT_EQ(sled::ToLower(" "), " ");
+    EXPECT_EQ(sled::ToLower(""), "");
+}
+
+TEST(ToUpper, String)
+{
+    EXPECT_EQ(sled::ToUpper("Hello World"), "HELLO WORLD");
+    EXPECT_EQ(sled::ToUpper("HELLO WORLD"), "HELLO WORLD");
+    EXPECT_EQ(sled::ToUpper("hello world"), "HELLO WORLD");
+    EXPECT_EQ(sled::ToUpper(" "), " ");
+    EXPECT_EQ(sled::ToUpper(""), "");
+}
+
+TEST(StrJoin, Empty)
+{
+    EXPECT_EQ(sled::StrJoin({}, ","), "");
+    EXPECT_EQ(sled::StrJoin({}, ",", true), "");
+    EXPECT_EQ(sled::StrJoin({}, ",", false), "");
+}
+
+TEST(StrJoin, Delim)
+{
+    EXPECT_EQ(sled::StrJoin({"a", "b", "c"}, ","), "a,b,c");
+    EXPECT_EQ(sled::StrJoin({"a", "b", "c"}, ",", true), "a,b,c");
+    EXPECT_EQ(sled::StrJoin({"a", "b", "c"}, ",", false), "a,b,c");
+}
+
+TEST(StrJoin, DelimSkipEmpty)
+{
+    EXPECT_EQ(sled::StrJoin({"a", "", "c"}, ","), "a,,c");
+    EXPECT_EQ(sled::StrJoin({"a", "", "c"}, ",", true), "a,c");
+    EXPECT_EQ(sled::StrJoin({"a", "", "c"}, ",", false), "a,,c");
+}
+
+TEST(StrSplit, Empty)
+{
+    EXPECT_EQ(sled::StrSplit("", ","), std::vector<std::string>());
+    EXPECT_EQ(sled::StrSplit("", ",", true), std::vector<std::string>());
+    EXPECT_EQ(sled::StrSplit("", ",", false), std::vector<std::string>());
+}
+
+TEST(StrSplit, Delim)
+{
+    // single delim
+    EXPECT_EQ(sled::StrSplit("a,b,c", ","), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b,c", ",", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b,c", ",", false), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b,c,", ","), std::vector<std::string>({"a", "b", "c", ""}));
+    EXPECT_EQ(sled::StrSplit("a,b,c,", ",", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b,c,", ",", false), std::vector<std::string>({"a", "b", "c", ""}));
+    EXPECT_EQ(sled::StrSplit(",a,b,c", ","), std::vector<std::string>({"", "a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit(",a,b,c", ",", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit(",a,b,c", ",", false), std::vector<std::string>({"", "a", "b", "c"}));
+
+    // multi delim
+    EXPECT_EQ(sled::StrSplit(",,a,b,c", ",", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit(",,a,b,c", ",", false), std::vector<std::string>({"", "", "a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b,c,,", ",", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b,c,,", ",", false), std::vector<std::string>({"a", "b", "c", "", ""}));
+    EXPECT_EQ(sled::StrSplit("a,,b,c", ",", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,,b,c", ",", false), std::vector<std::string>({"a", "", "b", "c"}));
+}
+
+TEST(StrSplit, MultiDelim)
+{
+    EXPECT_EQ(sled::StrSplit("a,b;c", ",;", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b;c", ",;", false), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b;c,", ",;", true), std::vector<std::string>({"a", "b", "c"}));
+    EXPECT_EQ(sled::StrSplit("a,b;c,", ",;", false), std::vector<std::string>({"a", "b", "c", ""}));
+    EXPECT_EQ(sled::StrSplit("a,b;c,", ";,", true), std::vector<std::string>({"a", "b", "c"}));
+}